Stinking Hot Down Under

The numbers are in: 2013 was the hottest year on record in Australia since records began.

WHO: Will Steffen, Australian National University, Canberra Australia

WHAT: A report on how many heat records were broken in Australia last year

WHEN: January 2014

WHERE: The Climate Council website

TITLE: Off the Charts: 2013 Australia’s Hottest Year (open access)

Last week in Australia it was stinking hot. I was texting with my brother (who is doing a PhD in Meteorology so is also a massive nerd like me) about the heatwave forecast and we came up with a new term for what an overnight minimum temperature should be called when it’s too high. We decided that an overnight low of 28.6oC should be called a ‘lower maximum’ because that’s too hot to sleep in.

Unfortunately, this is the new normal for Australia, which has just been shown in excellent infographic form by the Australian Climate Council. It was a banner year for Australia last year breaking all kinds of heat records and having the hottest average temperature since record keeping started in 1910.


It looks pretty, but it’s so hot the sand burns your feet. Mornington Peninsula, Vic (photo: Amy Huva)

It looks pretty, but it’s so hot the sand burns your feet. Mornington Peninsula, Vic (photo: Amy Huva)

Now, I know we Australians are a competitive people who always like to win, but breaking these records are not so much fun.

Nationally, the records broken were:

  •  Highest average temperature across the country 1.20oC higher than the 1961-90 baseline years
  • Highest mean maximum temperature across the country 1.45oC above the baseline years
  • Mean minimum temperature across the country of 0.94oC above baseline years
  • Hottest January on record
  • Hottest summer on record (Dec 2012-Feb 2013)
  • Hottest winter day on record – August 31st 29.92oC
  • Hottest September on record of 2.75oC above baseline
  • Hottest spring on record
  • Hottest December on record

Locally, some of the notable records were:

  • South Australia broke their spring monthly average temperature record by 5.39oC
  • New South Wales broke their spring monthly average temperature record by 4.68oC
  • Alice Springs had their hottest October day ever of 42.6oC
  • Canberra’s October was 2.5oC above average
  • West Kimberly in Western Australia was a shocking 4oC above average for October

Sea Surface Temperatures were record highest for January and February 2013 and of the 21 days Australia has ever had with a country-wide average temperature above 39oC there were 8 of them in 2013 and 7 of them happened consecutively in January 2013! Remember in the news when Australia had to create a new colour on their temperature maps? That was then.

Even worse, this extreme heat was not pumped up with the influence of El Niño, which normally makes years warmer. The year had no strong El Niño or La Niña effect, so it was a climate-changed year.

Since 1950, the number of heat records has beaten the cold records in Australia at a rate of 3:1 and in true Australian style; we’ve exceeded expectations and broken all kinds of records. This is the new normal, and it’s only going to get worse unless we stop burning carbon.

Infographic by the Climate Council.

Infographic by the Climate Council.

Extreme Overachiever Decade 2001-2010

The World Meteorological Organisation global climate report for last decade shows it winning all the most extreme awards.

WHO: The World Meteorological Organisation (WMO) in conjunction with these international experts and meteorological and climate organisations.

WHAT: The Global Climate Report for the decade 2001-2010

WHEN: July 2013

WHERE: Online at the WMO website

TITLE: The Global Climate 2001-2010 A Decade of Climate Extremes (open access)

The World Meteorological Organisation (WMO) recently released their wrap up of the last decade’s worth of global weather related data. Now, as you will all remember, climate is the long term trend of the weather (generally over a 30 year period) but it’s also important to keep track of the decade to decade trends, if not because 10 is a nice round number to deal with.

So what did the last decade’s report card look like? Turns out 2001-2010 was an overachiever when it came to records and extremes, which is bad news for all of us, really. The last decade was the warmest on record for overall temperatures and the speed of warming has amped up as well. The long term warming trend is 0.062oC/decade, but since 1970 it’s sped up to 0.17oC/decade.

Decade by decade temperature record (from report)

Decade by decade temperature record (from report)

If you only look at land surface temperatures 2007 held the record for hottest with 0.95oC above average, with 2004 the ‘least warm’ (there’s no long term cold records happening here) at 0.68oC above average.

If you look at sea surface temperatures, 2003 wins with 0.40oC above average and 2008 was the least warm at 0.26oC above average. The warmest year in the Northern Hemisphere was 2007 at 1.13oC above average and in the Southern Hemisphere 2005 wins with 0.67oC.

When it comes to rain, it’s a mixed bag. There were places that got more rain, there were places with drought, there were more extremes. South America was wetter than normal, Africa was drier than normal. Overall, 2002 was the driest year of the decade and 2010 was the wettest. The problem with rain patterns changing with climate change is that the location and the time frame changes. Instead of slow soaking rains, it’s extremes of dry spells followed by flash flooding.

The patterns of El Niño and La Niña switched back quite a lot during the decade, with El Niño generally creating warmer trends and La Niña creating cooler trends.

El Niño and La Niña trends for sea surface temperatures (from report)

El Niño and La Niña trends for sea surface temperatures (from report)

To qualify as an extreme event, an event needs to result in 10 or more people dying, 100 or more people being affected, a declaration of a state of emergency and the need for international assistance, which I think is a pretty high bar. But of course, since the last decade was overachieving, there were 400 disasters of this scale that killed more than 1million people.

Weather disasters represented 88% of these extreme events and the damage from these events have increased significantly as well as seeing a 20% increase in casualties from the previous decade. The extra casualties have been from some extreme increases in certain categories like heatwaves. In 1991-2000 6,000 people died from heatwaves. In 2001-2010 that jumped to 136,000 people.

The price of extreme weather events has also gone up with 7,100 hydrometeorological events carrying a price tag of $US1trillion and resulting in 440,000 deaths over the decade. It’s also estimated that 20million people worldwide were displaced, so this was probably our first decade of a sizable number of climate refugees. Internal displacement will be one of the biggest factors as people move away from the more extreme parts of their country to the places where it still rains (eg. from Arizona to Oregon).

Tropical storms were a big issue, with the report noting ‘a steady increase in the exposure of OECD countries [to tropical cyclones] is also clear’. It’s nice to see them point out that issues around extreme weather are not a developing world problem because they don’t have the infrastructure to deal with them, shown through the flooding in Germany and Australia last decade.

There was also a special shout-out to my homeland of Australia, for the epic heatwave of 2009 where I experienced 46oC in Melbourne and can attest to it not being fun. Of course, that epic heatwave was beaten by 2013’s new extreme map colour. However I noted Australia was getting pretty much all of the extreme weather effects over the decade. Ouch.

Australia – can’t catch a break (compiled from report)

Australia – can’t catch a break (compiled from report)

Even for the category of ‘coldwaves’ where the Northern Hemisphere saw an increase in freak snowstorms, the average temperature for the winter was still +0.52oC warmer than average.

Last decade was also setting lots of records in the cryosphere (frozen part of the planet). 2005-2010 had the five lowest Arctic sea ice records which have been declining in extent and volume at a disturbingly rapid rate in what is commonly known as the Arctic Death Spiral. There’s been an acceleration of loss of mass from Greenland and the Antarctic ice sheets and a decrease in all global glaciers.

Arctic Death Spiral (from report)

Arctic Death Spiral (from report)

The World Glacier Monitoring Service describes the glacier melt rate and cumulative loss as ‘extraordinary’ and noted that glaciers are currently so far away from their equilibrium state that even without further warming they’re still going to keep melting. Oh, and last decade won the record for loss of snow cover too.

Declining snow cover (from report)

Declining snow cover (from report)

Sea level has started rising faster at a rate of 3mm/yr last decade, which is double the historical average of 1.6mm/yr. Interestingly, sea level rise is not even across the globe due to ocean circulation and mass. In a La Niña year, the Western Pacific Ocean can be 10-20cm higher than the average for the decade, but there’s only one way sea levels are going as the water warms and expands and the ice sheets melt – up.

Sea level rise (from report)

Sea level rise (from report)

Finally, if all of that wasn’t enough bad news for you – the report looked at the gas concentrations in the atmosphere and found (surprise, surprise) that CO2 is up and accounts for 64% of the increase in radiative forcing (making our planet warmer) over the past decade and 81% of the increase in the last five years. Methane is responsible for 18% of the increase and Nitrous Oxides chip in 6%.

Does it make anyone feel better if I tell you the hole in the ozone layer isn’t getting bigger anymore?

Basically the world we live in is getting more extreme as it heats up at an ever increasing rate. Given that these are the changes we’re seeing with a 0.8oC increase in global average temperatures and that’s from carbon we burnt over a decade ago, how about we stop burning carbon with a little more urgency now?

Your odds just shortened – Aussie Heatwaves

Climate change has increased the chance of extreme heatwaves in Australia by more than five times.

WHO: Sophie C. Lewis and David J. Karoly, School of Earth Sciences and ARC Centre of Excellence for Climate System Science, University of Melbourne, Victoria, Australia

WHAT: Looking at how much influence human-caused climate changes are pushing Australian summers into more extreme heat.

WHEN: July 2013

WHERE: Geophysical Research Letters (DOI: 10.1002/grl.50673), pre-publication release

TITLE: Anthropogenic contributions to Australia’s record summer temperatures of 2013 (subs. req)

There’s some interesting research happening at my alma mater Melbourne University these days (go Melbourne!). Even if you weren’t there to experience the extreme summer of 2012-13 in Australia, I’m sure you all remember the new colour that had to be created by the Australian Bureau of Meteorology for the weather maps when they maxed out above 50oC, or maybe the new rating for bushfires of ‘catastrophic’ for the climate fuelled fires that are beyond just an extreme risk?

Extreme Heat in January 2013 (Bureau of Meteorology)

Extreme Heat in January 2013 (Bureau of Meteorology)

So, to answer that age-old question ‘exactly how much have we messed this up?’ these researchers looked at the historical monthly weather patterns, weather patterns with natural forcing only and patterns with natural forcing and human forcing and matched those up with what actually happened.

They looked at the average monthly mean temperatures, maximum temperatures and minimum temperatures and found that the monthly extremes are increasing faster than the daily extremes – that is that there are more months that are more overall extreme than there are days of extremes.

The historical data they used for the experiment was from 1850 to 2005, with the baseline climate data (what they used as a reference for ‘normal’) being 1911-1940 because 30 years of weather data makes a climate!

They then created experiments for the data with natural forcing only, with natural and human forcing and ran exciting statistical functions like a probability density function with a kernel smoothing function that almost sounds like a super-cool popcorn maker.

To double check for error, they used the second hottest summer temperatures to make sure they could pick out the human influences from the randomness that can be the data, thereby deliberately making their findings conservative.

Once they’d run their fun popcorn-sounding numbers, they calculated the FAR – Fraction of Attributable Risk, which is exactly what it sounds like – the fraction of the risk of something happening that can attributed to a cause.

So if our ‘bad guy’ is human-induced climate change, how much can we blame it for the Australian Angry Summer of 2012-13? Well, a fair bit.

When they compared the numbers, they had 90% confidence that there was a 2.5 times increase in extreme heat from human influences. When they compared 1976-2005 data and extended the model out to 2020, the fraction increased again to a 5 times increased likelihood.

Extreme heat is ‘substantially more likely’ because of humans burning fossil fuels, which are pretty bold words from research scientists – when there’s a greater than 90% chance of something they say ‘very likely’ where most people would say ‘very certain’. In their research, events that should have been occurring 1-in-16 years naturally were happening 1-in-6 years with the historical numbers and 1-in-2 years with the model out to 2020. Ouch – summer just got more uncomfortable more often.

MTSOfan, flickr

MTSOfan, flickr

For me, the kicker came when the paper pointed out that the 2012-13 summer in Australia came in a La Niña year. Extreme heat events normally come with an El Niño year – La Niña years are cooler with more rain. So the fact that the Angry Summer occurred in a La Niña year is scary – sea surface temperatures were average or cooler in some places while at the same time the Bureau of Meteorology was scrambling for new map colours.

The paper concludes that their research supports ‘a clear conclusion that anthropogenic climate change had a substantial influence on the extreme summer heat over Australia’ and that these kinds of events are now five times as likely to occur. Welcome to summers on climate change?

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.

Predicting Extreme Heat

WHO: Brigitte Mueller and Sonia I. Seneviratne (Institute for Atmospheric and Climate Science, Eidgenössiche Technische Hochschule (ETH) Zurich, Switzerland)

WHAT:  Seeing if you can predict extreme heat from a lack of moisture in the ground.

WHEN: July 16 2012

WHERE: Proceedings of the National Academy of Sciences of the United States of America

TITLE: Hot days induced by precipitation deficits at the global scale (subs required)

Using data correlations to try and predict extreme heat – useful for drought and disaster planning

I’m sure many of you rush out each week to get the newest copy of the Proceedings of the National Academy of Sciences when it hits the stands (yeah, I don’t either) but this paper came to my attention as something a bit interesting.

The researchers were hoping that there might be a relationship between how dry the soil is in the lead up to heatwaves and the extreme heat that follows. If extreme heat can be better predicted, then it’s easier for local or state governments and emergency services to prepare for it.

To measure lack of rain, they used the Standardised Precipitation Index (SPI) which is a measure of drought that only looks at rainfall (so doesn’t count water supply levels, water demand or runoff losses). The index works on a number system where -2 is exceptionally dry, zero is normal amounts of rain, and +2 is exceptionally damp. This paper looked at soil moisture across the globe, but as an example, here’s the SPI map for the USA this May/June when they started their severe heatwave in several parts of the country.

The paper found that there is a relationship, where lack of surface moisture is generally followed by extreme heat a few weeks later. Keep in mind though, the favourite saying of statistics people around the world: correlation does not mean causation. So while there may be a connection between dry soil and coming heatwaves, that doesn’t mean that dry soil causes heat waves of course.

Interestingly, the researchers found that the relationship between lack of surface moisture and extreme heat was asymmetrical – the correlation was stronger for really extreme heat and weaker for average heat. Which is good because it means this method can help predict the really horrendously hot days better than the averagely uncomfortable hot days.

Predicting the days when it’s so hot even the Koalas will ask for a drink (Velovotee, Flickr)

The data used was SPI data for 3, 6 and 9-months between 1979-2010, and a ‘hot day’ was defined as a temperature that was warmer than 90% of all the other days. The strongest correlation between lack of soil moisture and extreme heat was found in North and South America, Europe, Australia and China. This means that in those areas, localised research could be done to look at how to best predict the potential for extreme heat before it occurs, which will allow for emergency services to prepare for things like more hospitalisations from heat stroke or bushfire conditions, and give local governments time to make public service announcements to try and stay indoors and hydrated, etc.

What’s this got to do with climate change? Well, currently for the North American summer of 2012, the heat records are beating the cold temperature records by 10 -1. This is what climate scientists are talking about when they say carbon pollution is loading the dice for more extremes – normally there should be one record high for every record low. So if extreme heat is going to become more common in some places as we experience greater levels of climate change from continuing carbon pollution being poured into the atmosphere, being able to plan for it is a really good idea.