Hot Enough Yet? Warming in Western North America

How much and in what ways has the western part of North America warmed from climate change between 1950 and 2005?

WHO: Evan L. J. Booth, James M. Byrne and Dan L. Johnson, Water and Environmental Sciences, University of Lethbridge, Alberta, Canada

WHAT: Collating all of the weather station data from North America west of the Mississippi River and looking at the long term trends.

WHEN: 13 December 2012

WHERE: International Journal of Climatology (Int. J. Climatol.) Vol. 32, Issue 15 (2012)

TITLE: Climatic changes in western North America, 1950–2005

As we all know, climate change is a global problem with regionally specific impacts. How the climate changes will depend on what your local climate was originally like. So how much has the western end of North America changed from 1950 to 2005? That’s what these researchers in Alberta set out to discover.

Firstly, for this research paper their area of western North America is more than just the Pacific Northwest. They decided to go with everything west of the Mississippi River in the USA and everything west of Manitoba in Canada, which is pretty diverse in terms of climate ranging from desert to mountains to prairies.

Climate study regions (from paper) and Google maps (for geographic locations)

Climate study regions (from paper) and Google maps (for geographic locations)

The researchers wanted to look at 50 years worth of data so that they could take out the natural variations like El Niño and La Niña years as well as the Pacific Decadal Oscillation and just focus on the human-caused effects of warming (aka anthropogenic warming for those who like big words).

The researchers looked at several different climate indicators. They counted the number of frost days, the length of the growing season, number of warm days and warm nights, number of wet days (>5mm of rain), very wet days (wetter than >95% of all the other days), daily rain intensity, and annual rain totals.

They noted that while climate change will definitely increase the intensity of the hydrological cycle, the future trends of rain (where it will be, how much there will be) are much more difficult to predict. However, the overall trend found was for rain increasing in the Pacific Northwest (sorry Vancouverites!) more than other areas.

Another interesting thing they found was that natural variability in climate may be masking the effects of climate change in Canada more than in the USA, given the large number of extreme weather events recently observed in the US compared with relatively few extreme events in Canada. Which doesn’t mean we’re getting off scot-free Canada, it means climate change is coming for us later!

There were 490 weather stations that contributed data to the paper, which meant for some massive number crunching, added to the fact that they had to develop an additional computer program to convert all the US measurements into metric (Dear USA, please join the rest of the world and go metric!).

As you can see from the map above, the area was broken down into six different regions and analysed for climate trends. The results were:

Pacific Northwest

The Pacific Northwest saw a significant decrease in frost days at a rate of 2.4 days/decade and a significant increase in warm nights. There was a general increasing trend for all the other measurements – the growing season was extended, and all the rain indicators went up (yeah, winter really is getting wetter Vancouver). The researchers noted that the Pacific Northwest has experienced ‘significant warming’ over the 50 year period, and that the reduction in frost days has severe consequences for Pine Beetle infestations and increasing wildfires.

Frost days: significantly decreasing (from paper)

Frost days: significantly decreasing (from paper)

The one exception to the rule was Oregon, where a significant warm and dry patch in the southern part of the state is a sign of the Californian desert climate moving north as the temperature increases.

Rain totals: Dry patch over Oregon (from paper)

Rain totals: Dry patch over Oregon (from paper)

Northwest Plains (Wyoming, Montana, Alberta, Saskatchewan)

The Northwest plains saw a significant decrease in frost days at a rate of .16 days per year. There was a significant increase in the number of warm days and warm nights, with an increase in all other factors. While the increases in growing season and precipitation are beneficial so far, the researchers noted that continued warming will have detrimental effects on soil moisture and that the earlier spring runoff will pose challenges for water management.

Humid Continental Plains (North Dakota, South Dakota, Nebraska, Iowa, Minnesota, Manitoba)

Changes in this area were more extreme than the Pacific Northwest or the plains. There were significant increases in all indicators except for frost days, which saw a significant decrease. The researchers were concerned to note that warm nights are outnumbering cool nights in the continental plains by 5:1. The average rainfall is increasing by .11mm per year which will eventually have serious consequences as the paper notes that most farmland and urban areas in the continental plains are located on flood plains.

Gulf (Texas, Oklahoma, Kansas, Missouri, Arkansas, Louisiana)

The Gulf States saw the most significant increase in rain totals with annual averages going up by 2.8mm per year. There were also significant increases in the number of warm nights, wet days and rain intensity. While there was a significant decrease in the growing season length, it was most pronounced in the northern states and possibly linked to the significant decrease in frost days. Interestingly, there was a significant decrease in warm days, which the researchers think could be linked to the increase in rain (more clouds = less sunlight beating down on you).

American Southwest (Utah, Colorado, Arizona, New Mexico)

Climatically, this one is a real mixed bag going from amazing ski mountains all the way to New Mexican desert. However, there were still some overarching trends. There were significant increases in warm days and nights, rain totals, rain intensity and wet days. There was a significant decrease in frost days and an increase in very wet days and the growing season. The paper noted that while the increase in rain in the Southwest is currently positive, that growing extremes in temperature and the evaporation associated with it will likely negate this factor in the future.

One large concern was the decrease in frost days, given that much of the flow from the Colorado River comes from snowmelt, which was wonderfully understated as:

‘While best management practices may be able to mitigate the risk of widespread system failure, current levels of development in arid areas of the region may be unsustainable.’

This is scientist for ‘you either deal with this now, or something’s going to give in a really nasty way later’. Or, as one of my favourite climate bloggers Joe Romm says ‘Hell and High Water’ which will bring us the next Dust Bowl.

California-Nevada

The final segment in Western North America had significant decreases in frost days (as did all of Western North America), significant increases in warm nights and increases in all the other indicators. This may seem milder; however the researchers warn that California had substantial warming with only a slight increase in precipitation. This will be deadly as climate change continues. As the paper states:

‘A decline in the availability of water supplies may make the current intensive agriculture industry in California’s Central Valley unsustainable in the long term.’

Did you hear that? It’s the sound of your favourite Napa wine grapes shrivelling and dying in the heat.

The end of irrigated agriculture in California? (photo: flickr)

The end of irrigated agriculture in California? (photo: flickr)

So what does this all mean? Well, long story short it means that while we here in Canada aren’t experiencing the worst of climate extremes yet, and while each region of North America will change specifically based on their local climate, we haven’t seen anything yet.

The long term trends are pretty clear for most areas (or at least statistically significant) and the consequences for communities and industries aren’t good. And that’s even before you start to think about non-linear climate responses and ecosystem tipping points. So, for the sake of the wine in Napa, the skiing in the Rockies, the agriculture in the prairies and the people who call New Mexico home, let’s stop burning carbon.

World Bank Wants off the Highway to Hell

“It is my hope that this report shocks us into action… This report spells out what the world would be like if it warmed by 4 degrees Celsius… The 4oC scenarios are devastating.” Dr. Jim Yong Kim President, World Bank

WHO: The Potsdam Institute for Climate Impact Research and Climate Analytics, commissioned by the World Bank

WHAT: A report looking at the impacts of 4oC of global warming and the risk to human systems

WHEN: November 2012

WHERE: The World Bank’s website

TITLE: Turn down the heat: Why a 4oC warmer world must be avoided

Following on from last week’s Highway to Hell post, the World Bank released a report looking at the human system implications for climate change because things that disturb the current systems of running the world tend to be expensive for organisations like the World Bank.

The report looks at climate change projections for a 4oC world, most of which I’ve already covered on this blog like; ocean acidification, droughts, tropical cyclones, sea level rise and extreme temperatures. So I’m going to skip ahead to the chapters on impacts in different sectors and then my personal favourite, non-linear impacts. This week will be sector impacts.

It’s refreshing to see an organisation that is normally known for its staid and stuffy conservatism talking about climate change reality. The foreword by the World Bank’s President says no less than that the science is unequivocal, that warming of 4oC threatens our ability to adapt and that meeting the currently agreed upon UNFCCC targets (which we’re not meeting) will lead to 3.5-4oC warming which must be avoided through greater and more urgent action now.

Let’s look at what this bastion of the three piece suit with not a dreadlock in sight says about the impacts that could be felt in a 4oC world.

Agriculture
Generally the impacts for agriculture will be regionally specific, as will the impacts for climate change. Some regions will get more rain, some less rain, and the timing of the seasons will change.

The favourite argument of luke-warmists is that increased CO2 in the atmosphere is excellent because it will benefit agricultural growth and we’ll be able to grow lettuce in Siberia. Well, yes and no – it’s more complex than that. Between 1-3oC of warming it’s likely we’ll see increased yields in certain regions from CO2 fertilization. Beyond 3oC productivity will decrease as the stresses of other climate change impacts outweigh any benefit from extra CO2.

And even then, demand from a world population growing to a projected 9 billion by 2050 is going to increase demand by 70-100% for agricultural food products, so even without the costs of climate change reducing the productivity of crops, it’s going to be difficult to feed the world with that many people.

Another vulnerability for agriculture is sea level rise and salination of some of the world’s most productive agricultural land. Having to move your farm from a nutrient rich delta to less productive soil further inland will detrimentally affect crop yields.

Finally, the benefits of CO2 fertilisation will be limited by the availability of other nutrients. You can give a plant all the CO2 it wants, but if you don’t also give it nitrogen, phosphorus and water, it’s not going to grow any faster. It’s currently looking like there’s going to be a world shortage of phosphorus based fertilizer, which will have a very detrimental affect on world crops that need to be becoming more productive to feed a growing population, not less.

Water Resources
This section starts with a very obvious statement that is useful to point out: ‘The associated changes in the terrestrial water cycle are likely to affect the nature and availability of natural water resources and, consequently, human societies that rely on them.’

We rely on the services that the environment provides for us and the second most important one of these is water (the first one is air).

As well as the expected (and already occurring) more severe droughts, river runoff is expected to decrease significantly in areas where the water is used for both agriculture and transport like the Danube, the Mississippi, the Amazon and the Murray-Darling Basin in Australia.

In a 2oC warming world, most of the water stresses can be expected to be from population increase. By the time we get to a 4oC world, the stress of climate change will outstrip that of population increase. Even in the areas where there will be increased rainfall, it’s not likely to come at the right time of the year, or it could come all at once causing flooding.

There’s a lot of uncertainty in many models of drought prediction and rainfall prediction as well as the possible effects for specific regional areas, but the conclusions that are coming from all of the studies identified in this report range from bad to very bad, and in a 4oC world almost half of the world’s population could be water stressed by 2080.

Ecosystems and Biodiversity
This is the fun section that starts using terms like ‘mass extinction’ and gets everyone Googling things like the Eocene.

Biodiversity is, in my opinion going to be the ‘sleeper issue’ of climate change, because it happens over longer periods of time and is easy to ignore as out of sight out of mind for us urbanites until it’s too late. As the report quotes; ‘It is well established that loss or degradation of ecosystem services occurs as a consequence of species extinctions’.

There’s also the issue of thresholds. Where an animal or plant or ecosystem can absorb a certain amount of degradation, until you reach the tipping point and it can no longer take it. Some areas will be able to absorb more warming (Canada, Northern Europe) while others may reach biodiversity and ecosystem tipping points earlier (Pacific Islands, Bangladesh).

In a 4oC world, it’s possible that habitats could shift by up to 400km towards the poles, which is fine if you’re a mosquito moving north from Mexico, but not so good if you’re a mountain rabbit and you run out of mountain.

And here’s some food for thought: the report states that if the planet lost all of the species that are currently listed as ‘critically endangered’ we would officially be living through a mass extinction, and if we lost the species that are also ‘endangered’ or ‘vulnerable’ we would be confirmed as the sixth mass extinction in geological history. Which means history would list the dinosaurs and then the humans in the fossil record of mass extinctions.

As the report says: ‘loss of biodiversity will challenge those reliant on ecosystem services’. This means all of us.

Human Health
Like smoking, climate change is bad for your health. The above mentioned agricultural and water issues with a 4oC warmer world will lead to famine and malnutrition on a large scale. The extreme weather events from a planet on climate steroids will kill people in heat waves, increase respiratory diseases and allergies from the extra dust in the droughts, weaken existing health services through damage to hospitals in extreme storms, flooding and so on.

Living with constant extreme weather is bad for your mental health, whether it’s the slow and painful crush of watching drought destroy your farmland or the fast emergency of cyclones, hurricanes and floods.

And remember the mosquitoes moving north? They’ll bring new tropical diseases with them that will infect many new people who have never developed any immunity to them.

Given all of the above, it’s pretty clear why the World Bank wants off the highway to hell. Because they’re concerned about both loaning money to countries that are dealing with these catastrophes, and living through these impacts. Because, as all of my fellow Gen Ys already know, living these impacts by 2050 is not some vague and distant future. It’s before we all retire.

 

Next week: non-linear impacts, which are scarier than they sound. 

The Forests of Planet Ocean

Estuaries are the forests of the ocean and they take up carbon 90 times more efficiently than land forests

WHO: Colin Campbell (Science Advisor, Sierra Club BC, PhD Marsupial Evolution, UC Berkley)

WHAT: ‘Blue Carbon’ report looking at how carbon is stored in oceans

WHEN: August 2010

WHERE: Sierra Club BC – in print and online

TITLE: Blue Carbon British Columbia: The Case for the Conservation and Enhancement of Estuarine Processes and Sediments in B.C.

Since I’ve moved to Canada, I’ve learnt a lot about salmon and it’s a pretty tough gig from what I can tell. Everyone wants to eat you along the way (including humans like me – yum!) and evolution decided it would be a good idea to swim up the river – way to make it harder!

Salmon – it’s a hard knock life (photo: Dan Bennett, flickr)

But even harder again – once baby salmon have hatched and are swimming back down the river to eat and grow and become edible for me, they have to also make the switch into salt water which is impressive in any animal.

Changing from fresh water to salt water as a fish takes a whole heap of osmoregulation, which is the transfer of water into and out of your cells to keep an even salt balance on both sides of the cell membrane. When there’s too much salt on one side, the water moves to dilute it, which is the reason we feel dehydrated after eating a lot of salty food. So a salmon changing to salt water would be like you or I changing to only drinking salt water instead of fresh water. Salmon can do this, we would not survive.

How do salmon do this? Well it involves estuaries. Estuaries are the underwater grasslands at river mouths which look pretty gross to walk through in your bare feet when you’re going swimming. But if you’re a salmon, it’s your training ground. Salmon will hang out in estuaries full of eelgrass or salt marshes for a week or two until their bodies switch to salt water. The area is full of microbes dissolved in the water for the salmon to eat and the eelgrass provides a great hiding place for salmon that aren’t yet fast enough to swim away from everyone who wants to eat it. Without estuaries, the salmon race down the river and shoot straight out into the salt water, which is quite a shock to their systems.

Eelgrass – salmon training ground and underwater forest (photo: Eric Heupel, flickr)

This paper from the Sierra Club here in British Columbia talks about estuaries other feature – they’re great carbon sinks, and we need more of them. Carbon moves around our planet in a cycle with sources and sinks. Humans burning fossil fuels are a huge source of it and the sinks can’t keep up the balance (hence ocean acidification and global warming). So the more carbon sinks we can preserve and create the better for our survival.

Because eelgrass, mangroves and salt marshes are in the shallow water, they get lots of sunlight, which allows them to photosynthesise. 1km2 of mangroves can store the same amount of carbon as 50km2 of tropical rainforest and estuaries are constantly sucking carbon dioxide in, and releasing oxygen while pushing carbon further down into the sediment on the ocean floor.

They suck carbon in, send oxygen out and provide a training ground for animals – so far there’s no downside.Except that many estuaries have been or are being reduced by human development. In the Fraser River here in Vancouver alone, 99% of the delta marshlands are gone due to flood prevention dyking, farmland or development. That’s a whole lot of carbon that could be sucked into the estuary that isn’t.

Currently, it’s estimated that BC estuaries sequester 180,200 tonnes of carbon per year, even with their diminished size due to humans. When you realise that Metro Vancouver’s carbon emissions were 10.5 million tonnes in 2010, estuaries take up 1.7% of our emissions each year. If we keep burning carbon, we will need a lot more estuaries. Additional benefit for our own self interest as well of course is that more estuaries means bigger salmon runs and more delicious food for us, the bears, the seals, the whales, the eagles and all the rest.

As Vancouver aims for its 2020 Greenest City targets, one of the most efficient ways of sequestering more carbon while also reducing our emissions might not be our forests, but our underwater forests – the tidal estuaries.

Predicting the Unpredictable: Tropical Hydrology

Unpredictable tropical storms from climate change and changing land-use patterns are going to mess with water cycles

WHO:  Ellen Wohl (Department of Geosciences, Colorado State University, Fort Collins, Colorado)
Ana Barros (Duke University, Pratt School of Engineering, Durham, North Carolina)
Nathaniel Brunsell (Department of Geography, University of Kansas, Lawrence, Kansas)
Nick A. Chappell (Lancaster Environment Centre, Lancaster University, Lancaster, UK)
Michael Coe (Woods Hole Research Center, Falmouth, Massachusetts )
Thomas Giambelluca (Department of Geography, University of Hawaii at Manoa, Honolulu, Hawaii )
Steven Goldsmith (Department of Geography and the Environment, Villanova University, Villanova, Pennsylvania)
Russell Harmon (Environmental Sciences Division, ARL Army Research Office, North Carolina)
Jan M. H. Hendrick (New Mexico Institute of Mining and Technology, Socorro, New Mexico)
James Juvik (Department of Geography and Environmental Studies, University of Hawaii-Hilo, Hilo, Hawaii)
Jeffrey McDonnell (Department of Forest Engineering, Resources, and Management, Oregon State University, Corvallis, Oregon)
Fred Ogden (Department of Civil and Architectural Engineering, University of Wyoming, Laramie, Wyoming)

WHAT: Looking at what we know about tropical water patterns and working out what we don’t know

WHEN: September 2012

WHERE: Nature Climate Change, Vol 2 Issue 9, September 2012

TITLE:  The hydrology of the humid tropics (subs. req)

This paper from Nature Climate Change does two things; it looks at what we know about tropical water cycles (hydrology) and also the gaps in our knowledge (scientists- always wanting to know more!).

So what do we know?

Firstly, let’s define the ‘tropics’. This paper looks specifically at the humid tropics which is anywhere that precipitation exceeds evaporation 270 days a year or more, and is generally 25⁰ latitude either side of the equator.

The tropics highlighted in red (Wikipedia)

Fun fact – the tropics is where the term ‘the doldrums’ comes from. It’s officially known as the ‘Intertropical Convergence Zone’ and is the area where the winds coming from the northern hemisphere and the southern hemisphere collide, creating erratic weather patterns and violent thunderstorms. This poses a few issues in the face of climate change. Climate change will make weather more extreme and the effects will be non-linear, so this means the tropics are about to get even less easy to predict.

There are many areas of the tropics where land-use changes are affecting water cycles. Deforested areas outnumber the remaining forest, which is already having a measurable effect on rain patterns in Brazil; extending the dry season and rain being more intense when it does occur. It’s estimated that deforestation in the South Eastern Amazon has increased the flow of water to the ocean by 20% in the last 40 years. These changes and others will likely be amplified with increased climate change effects.

Billions of people rely on the major rivers in the tropics for their fresh water, and flows of water, energy and carbon are all closely linked to the amount and age of vegetation in the area. Changes in water flows and rain patterns can be disastrous, and can occur from combinations of land-use change, deforestation and climate change. So messing with the systems can create large changes. The closely linked relationship between vegetation type and water cycles also means that my idea of trying to grow an Australian gum tree here in Vancouver when I feel homesick is a bad one.

However, while water cycles are being modified across the tropics by land-use changes, deforestation and climate change, the effects are going to vary region by region, making predictions difficult. There are far fewer weather measuring stations in tropical areas than temperate areas, so less data overall. The researchers identified moisture cycling, water catchment processes and long term data collection as areas that need improvement if we are going to be able to accurately predict global warming changes in the tropics.

Number of weather stations in temperate vs tropical areas (from paper)

In order to answer important questions that relate to the availability of fresh water for billions of people and extreme weather in areas that have earthquake activity as well as cyclones there needs to be a detailed body of data. Forewarned is forearmed, especially if systems are heading towards possible tipping points, and this paper would like researchers to study more tropical areas to better understand them.

Busting our Carbon Budget: Siberian Permafrost

Siberian permafrost is releasing ancient carbon much faster than previously thought

WHO: J. E. Vonk, L. Sánchez-García, B. E. van Dongen, V. Alling, A. Andersson, Ö. Gustafsson (Department of Applied Environmental Science (ITM) and the Bert Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden)
D. Kosmach, A. Charkin, O. V. Dudarev (Pacific Oceanological Institute, Russian Academy of Sciences, Vladivostok, Russia)
I. P. Semiletov, N. Shakhova (Pacific Oceanological Institute, Russian Academy of Sciences, Vladivostok, Russia and International Arctic Research Center, University of Alaska, Fairbanks, Alaska)
P. Roos (Risø National Laboratory for Sustainable Energy, Roskilde, Denmark)
T. I. Eglinton (Geological Institute, ETH-Zürich, Zürich, Switzerland)

WHAT: Measuring and calculating the carbon released from thawing and eroding permafrost in far northern Russia

WHEN: 6 September 2012

WHERE: Nature, Vol 489, 137-140

TITLE: Activation of old carbon by erosion of coastal and subsea permafrost in Arctic Siberia (subs req.)

Those of you who read the recent Bill McKibben article in Rolling Stone magazine about the planet’s atmospheric carbon budget will know ~565 Gigatonnes is the amount of carbon pollution that humans can still burn and hope to avoid catastrophic climate change. Beyond that, we’re playing Russian roulette with extra bullets loaded.

Why am I talking about Rolling Stone when this paper is talking about Siberia? Well, the researchers for this paper went to far northern Russia to work out how much coastal Siberian permafrost is being eroded away, releasing the carbon into the atmosphere and spending our ever shrinking carbon budget.

Muostakh Island (point A, Google maps)

The Arctic permafrost in Siberia holds ~1,000 Gigatonnes of carbon frozen on land, ~400 Gigatonnes of coastal carbon and ~1,400 Gigatonnes of sub-sea carbon. So if this permafrost starts thawing and releasing carbon at a great rate, we humans have totally bust our carbon budget and the future is looking pretty horrifying; much like the greenhouse extinction from last week’s post.

So is it thawing out? And how fast?

The Island of Muostakh in the north of Russia has been eroding at a rate of up to 20m per year, and this is where the researchers went to try and measure the amount of carbon that is being released into the atmosphere.

Eroding cliffs on Muostakh Island (from paper)

They used a dual carbon-isotope mixing model solved with a Monte Carlo simulation strategy, which is sadly not a really tasty sounding desert, but a way of working out which carbon isotopes are from plankton, topsoil or old carbon which is the stuff they’re interested in (they used 13C and 14C isotopes for those playing at home).

Through the isotope analysis they found a coastal permafrost carbon release of 22 Megatonnes (.022 Gigatonnes) of carbon per year from erosion. Additionally they estimate that 66% of the old carbon that is washed into the ocean degrades downstream and is released into the atmosphere instead of sinking to the sea floor. Previous research had thought that carbon from coastal erosion washed into the ocean without releasing into the atmosphere.

Once you combine the carbon eroded with the 66% downstream degradation, the total atmospheric release is 44 Megatonnes (.044 Gigatonnes) of carbon per year which is much larger than the previously estimated 4 Megatonnes of carbon per year. This large difference may be because of methods used in previous research, unaccounted for changes in coastal elevation (the higher the cliff, the harder for the waves to reach it) or not counting the sub-sea degradation.

Either way, the idea that we may be under-counting the amount of carbon released from thawing and eroding Siberian permafrost has some serious implications for all of us. We are currently polluting the atmosphere with carbon at a rate of 31.6 Gigatonnes per year and rising. As we continue to burn carbon, the permafrost in Siberia will thaw and erode faster, increasing from the current rate of .044 Gigatonnes per year.

We are quickly running out of time and atmospheric space to stop runaway climate change. If even half the sub-sea permafrost is released as atmospheric carbon, we’ve surpassed 565 Gigatonnes. Hopefully the increased and continued thawing of the Siberian permafrost isn’t the bit that busts our carbon budget.

It’s Getting Hot in Here: A Brief History of Antarctic Warming

The melting and re-freezing of Antarctic ice sheets has always happened on a millennium time-scale. This time, we’re doing it in decades…

WHO: Robert Mulvaney, Richard C. A. Hindmarsh, Louise Fleet, Jack Triest, Louise C. Sime, Susan Foord (British Antarctic Survey, Natural Environment Research Council, Cambridge, UK)
Nerilie J. Abram (British Antarctic Survey, Natural Environment Research Council, Cambridge, UK and Research School of Earth Sciences, The Australian National University, Canberra, Australia)
Carol Arrowsmith (NERC Isotope Geosciences Laboratory, Keyworth, UK)
Olivier Alemany (Laboratoire de Glaciologie et Geophysique de l’Environnement (LGGE), Grenoble, France)

WHAT: Taking a giant (363.9m) ice core sample in Antarctica to look at climate history

WHEN: 6 September 2012

WHERE: Nature 489, September 2012

TITLE: Recent Antarctic Peninsula warming relative to Holocene climate and ice-shelf history (subs. required)

There’s been a lot of press recently about the Arctic Death Spiral which is of great concern to the stability of our climate, and means the poor southern cousin of the Arctic – the Antarctic doesn’t get much of a look in. No Santa, not as much media, what’s even happening with those penguins down south?

Penguin! (KK Condon, flickr)

Well, it’s melting too, which is unsurprising given that the whole planet is heating up, but this group of British, Australian and French researchers have put together a short (~50,000 years) history of ice melt and temperature changes from their ice core. (How did the researchers know I did history AND science?!)

They drilled an ice core on James Ross Island that is 363.9m long (which gives a bit of perspective as to how much ice is in the Antarctic if it’s 363.9m deep!) and looked at the ratio of isotopes to work out what the climate and temperature was like. Isotopes are elements that are the same but have a different weight because of an extra neutron (the bits in an atom that have a neutral charge). Different isotopes occur naturally at different amounts – for instance, Carbon with a weight of 12 is the most common on earth and Carbon 13 (one neutron heavier) is found 1% of the time. This research looked at Hydrogen vs Deuterium isotopes.

James Ross Island, Antarctica (from paper)

Different isotope ratios can tell us what was and is going on in the atmosphere and 363.9m of ice core can tell us approx. 50,000 worth of history (the paper uses BP = before present. For some strange reason ‘present’ time is 1950, but then I guess BC and AD are just as arbitrary).

50,000 years BP was the last glacial interval before the Holocene, the current geological period we live in (although there’s an argument that we’re now living in the Anthropocene), all of which is in the ice core. There was a glacial maximum (26,000 – 20,000 years BP) which was 6.1C colder on James Ross Island than present and an early climactic optimum (warmest part) of the Holocene which was 1.3C warmer than present. Marine sediment samples show the ocean was 3.5C warmer.

Sustained warming on James Ross Island started occurring around 600 BP (1450AD for us) with a rate of .22C of warming per century. This cranked up with rapid warming between 1518 – 1621 and 1671 – 1777 of more than 1.25C.

The warming over the past 100 years has been the fastest warming seen in 2000 years, but it’s not yet out of the range of normal warming and cooling patterns for the Antarctic. However, the most recent phase of warming started in the 1920s (so will be more influenced by industrial and human pollution than the earlier warming) and it’s going at a rate of 2.6C per century. Which is double the rate of the natural warming above.

What does faster warming mean for Antarctic ice sheets? The rapid warming means the ice becomes unstable, and the researchers say that continued warming at the pace currently being observed could lead to an ice sheet collapsing. Additionally, if the warming continues, it will start melting the southern ice sheets that were stable in the earlier Holocene warm period.

So why should we, sitting at our computers a long way from the Antarctic care about melting ice sheets? Well other than the huge inconvenience that’s going to be for a whole range of cute animals like penguins whales and seals, melting ice sheets on land cause sea level to rise. The melting of the Arctic is certainly of concern for Northern Hemisphere weather patterns, but the melting of floating ice, doesn’t change sea level.

The melting of ice that is on an island does raise the sea level. And the melting of the entire Antarctic ice sheet would contribute an extra 60m to sea level. Which is horrifying, and a really good reason to care about the speed of melting in Antarctica. That kind of rise puts my hometown of Melbourne totally underwater (elevation 31m). It puts half of Vancouver underwater (elevation 0 – 152m) and all of London as well (elevation 24m).

Now, obviously the total melting of the Antarctic ice sheet is going to take a long time given how large it is. However, it’s really difficult to stop once started. And given that I keep talking about how climate change is going to be non-linear and unpredictable when feedbacks unexpectedly kick in from tipping points, I’d argue we shouldn’t be playing Russian roulette with this one and we should stop burning carbon instead.

[EDITED 21 Sept. to reflect the note from the lead author of the paper that an ice sheet is on land and an ice shelf is floating in water – AH]

Sea Level Rise and the Effects of Carbon Pollution Reduction

WHO: Michiel Schaeffer (Environmental Systems Analysis Group, Wageningen      University, The Netherlands),
William Hare (Potsdam Institute for Climate Impact Research, Potsdam, Germany),
Stefan Rahmstorf (Potsdam Institute for Climate Impact Research, Potsdam, Germany),
Martin Vermeer (Geoinformatics, Aalto University School of Engineering, Finland)

WHAT: Estimates of sea level rise with different levels of CO2 emission reduction

WHEN: 24 June, 2012

WHERE: Nature Climate Change, Vol 2 Issue 7 2012

TITLE: Long-term sea-level rise implied by 1.5 °C and 2 °C warming levels

One of the consequences of climate change is going to be sea level rise as the globe slowly warms and ice sheets and glaciers continue to melt.

The issue is trying to predict exactly how much sea level is going to rise by and how much we can do about it. This paper was published in June in the journal Nature Climate Change, which is an offshoot of the journal Nature, one of the most highly respected peer reviewed scientific journals in the world.

The researchers used several different scenarios for looking at how sea levels rise with rising temperatures and used what’s called a semi-empirical model to predict the numbers out to 2100 and 2300.

A semi-empirical model is one that combines observed and recorded data (thermometers, tide records) with paleo data (ice cores, fossil records). Since there is only recorded tide gauge data from the previous 130 years, this is not a large enough sample to use for long range predictions. It would be like using one week of training to determine whether I could run a marathon. So the researchers combined the historical data with the recorded data and calibrated to test how realistic the combination was.

Calibrating is where you test something for a single result several times and work out what your error margin is. For example, you could measure three different bottles of Coca Cola you bought at the store, and one might have 600mL, one might have 603mL and the third might have 598mL. They’re all supposed to be 600mL, but since most things have a margin of error, not all are exact.

Same thing for science experiments. The researchers calibrated their data for the years 1000 through to 2006 and found that their results were similar to other scientists who had done similar experiments.

Several scenarios were used; two with no reductions in carbon emissions (from the Copenhagen Accord agreement), two where the earth stays within 2C of warming (one that looks at all polluting gasses – carbon, ozone and sulphur based and one that looks at the delay of emission reductions until 2100), and one where the earth stays within 1.5C of warming (with early carbon emission reductions keeping pollution under 400 parts per million (ppm) in the atmosphere).

Three of the scenarios (delaying until 2100 and two in between) used data that will be included in the IPCC 5th Assessment Report which is the newest data on climate change. The finalised 5th report won’t be published by the UN until the end of 2014.

One of the scenarios for 2C (the one with the different polluting gasses) was developed by an international scientific group and published in Climactic Change. The scenario for 1.5C was developed by a group working for the International Energy Agency and published in the journal Energy. Another hypothetical scenario where global carbon emissions are zero by 2016 was also used to see what effect historical emissions might have on sea levels.

So what did they find? Already, the data for the 20th Century (1900-1999) has higher sea levels than any time in the past 1,000 years.

Using the scenario from the Copenhagen Accord (the equivalent of doing nothing) a sea level rise of 72 – 139cm by 2100 was predicted.

Even with zero emissions by 2016 there’s a predicted sea level rise of 40 – 80cm by 2100. The reason for this is because climate systems are inert. Which means they can absorb a lot of change before you can see it and that there’s a time lag between putting the pollution into the atmosphere and seeing the consequences.

Sea level rise precitions (MERGE400 = 1.5C, Stab2 and RCP3-PD = 2C, CPH = no action, others are variations in between). Dark lines are the median (middle) predictions, shaded areas show the uncertainty range.

So what does this mean in reality for climate change and people? It means that even if we limit carbon pollution in the atmosphere to 400ppm the conservative estimate is for a 54cm rise in sea level, which is knee-deep on me. And if 400ppm doesn’t sound like a very big number, just remember the US EPA recommends that more than .002ppm of mercury in your drinking water is dangerous. You don’t need large amounts of compounds for them to be dangerous to your (or the planet’s) health.

The good news is the research shows that even though there’s uncertainty regarding non-linear (unpredicted) changes in ice sheet melt, and we’re going to experience sea level rise continuing over the next 50 years from pollution already in the atmosphere, emissions reductions do show less sea level rise than the ‘do nothing’ or ‘delay’ scenarios.

So while we are going to have around half a metre of sea level rise in the next 50-100 years (I’d hold off on purchasing that beachfront property), with strong emission reductions, the sea level might peak sometime before 2100 and hopefully head back towards normal.

Why the huge range of numbers and years? Firstly because the researchers can’t say what and how much the world is going to do about climate change in the next few decades, and secondly because you can’t be absolutely (as in 100%) certain that anything is going to happen until it actually does. But the data gives us a pretty clear indication that the year 2100 will see somewhere between .5 – 1m of sea level rise.