For climate science, the year 2009 brought significant discoveries and startling controversies. We’ve got a wrap-up from Kurt Kleiner of the top ten climate science stories of the past twelve months over on Nature Reports Climate Change.
A more detailed version here, but in short, they are:
1. Warming goes global
The year started out with some sobering, if not altogether surprising, news: overall, the Antarctic continent is warming. In Januray, climatologist Eric Steig of the University of Washington in Seattle and colleagues reported (Nature 457, 459–462; 2009) that warming was widespread across the continent. This was backed up by another study in October, published in Geophysical Research Letters, which reported that the southwestern Antarctic Peninsula showed warming of 2.7 °C over the last 50 years.
2. Confusion over cooling
In March, a rather technical paper discussing climate periodicity was widely misinterpreted as suggesting that we are in a period of global cooling, and much energy was expended trying to set the record straight. In September, Mojib Latif, a climatologist at the Leibniz Institute of Marine Sciences at Kiel University in Germany, noted that because of natural variability in the climate, it is theoretically possible that we could see “a decade, or maybe even two, when the temperature cools relative to the present level”. Some news accounts reported that Latif had predicted global cooling, and climate change deniers echoed the claims. Lost in the ensuing game of telephone was the fact that in both cases the researchers accept that overall warming is occurring and will continue in the long run.
3. Settling the score on sea level
The case on sea level isn’t closed, but this year several studies have shown it could rise a metre or more by 2100. In March a Climate Change Congress in Copenhagen reported that sea levels could rise as much as one metre by 2100. Part of the increase will come from ‘thermal expansion’ — oceans are apparently warming 50 per cent faster than was previously thought, and water expands as it heats up. The other part of the predicted rise comes from ice sheets melting more rapidly than expected in Greenland and Antarctica.
4. More talk about targets
Amidst continued discussions on targets — whether to stabilize atmospheric carbon dioxide concentrations at 450 or 350 parts per million, and whether peaking global emissions by 2015 or 2020 will be enough to avoid catastrophic warming — a group of scientists suggested it would be easier to concentrate on one nice round number. The number? One trillion tonnes. That’s the limit we should place on our cumulative carbon dioxide emissions if we are to have a reasonable chance of avoiding warming above 2 °C, said Myles Allen of the University of Oxford and colleagues (Nature 348, 1163; 2009).
5. Climategate causes more confusion
Just ahead of the December UN negotiations on a climate deal, thousands of e-mails and documents were stolen from a server at the University of East Anglia Climatic Research Centre in the UK and posted on the internet. Predictably dubbed ‘Climategate’, the incident caused delight among climate change deniers and major embarrassment for some climate scientists — especially the centre’s director, Phil Jones. The e-mails show researchers speaking privately to one another, and it’s not always pretty. What the e-mails do not show, however, is a grand conspiracy to concoct global warming. Instead, they show sincere researchers struggling to do good work in a highly politicized environment — and sometimes losing their tempers.
6. Overshooting and adapting
With carbon emissions still rising, and political foot-dragging continuing, some scientists began to consider what the world will look like if we miss the target of limiting global temperature increase to 2 °C above pre-industrial levels.
At a conference in September, scientists present their results on what a 4 °C world would look like. Among other things, we could look forward to the destruction of US$1 trillion worth of gross domestic product and displacement of 146 million people if sea levels rise a metre, as well as starvation, disease, fire and flooding.
7. Geoengineering gains ground
During 2009, geoengineering took a few steps away from science fiction and towards reality. The idea that we ought to consider actively taking control of the climate has previously seemed fanciful, if not downright dangerous. But as emissions have continued to rise, the idea has become less marginalized. Even still, authors Steven Levitt and Stephen J. Dubner took it a step too far in their book SuperFreakonomics, when they proposed geoengineering as a fast and cheap solution to the climate problem.
8. Aerosol cooling questioned
Man-made aerosols have been thought to counter global warming by reflecting solar radiation directly and also by lengthening cloud lifetimes. But a review published in October suggests that aerosol cooling is probably minimal, and a new study finds that their influence on climate can by affected by how they interact with greenhouse gases. The jury is still out on the overall influence of these tiny air-based particles.
9. Hoopla over Himalayan glaciers
In November, the Indian Ministry of the Environment and Forests released a controversial report from a retired glaciologist claiming that glaciers in the Himalayas are not melting in the face of global warming. The report sparked angry responses from some scientists, outraged that it hadn’t been peer-reviewed and was based on a sample of just 25 glaciers. But Kenneth Hewitt, a glaciologist from Wilfrid Laurier University in Waterloo, Ontario, told the BBC that some Himalayan glaciers are, in fact, advancing. Changes in glaciers seem to vary depending on location and elevation, and there’s not enough data to draw a general conclusion. “Climate change is happening here too, but with different consequences,” Hewitt said.
10. Climate science on demand
With emissions continuing to rise, governments looked to scientists for greater certainty on how climate change will play out at the local level. Regional projections released for the UK in July cause a ruckus over concerns that the results “stretched the ability of current climate science”.Despite the concerns, governments worldwide are keen to follow the UK’s lead and to learn from its mistakes. In July, Germany opened the first national Climate Service Center in Hamburg. The United States announced its intention to start a National Climate Service. In September the World Meteorological Organization held a conference in Geneva and instituted a Global Framework for Climate Services to facilitate climate data sharing among countries.