A Dutch-led team of European researchers have considered multiple scenarios for tackling global warming and outlined the impact on the planet as various levels of emissions-mitigating strategies are employed.
The message: Avoiding warming this century of more than 2 degrees (celsius) will require mitigation efforts at the top of the range currently being considered.
Humans therefore must adapt to meet new conditions brought about by climate change whatever mitigation efforts are undertaken.
To download the report, published by the US National Academy of Sciences, click here.
According to the research, emissions will increase 70 percent to 250 percent from levels in 2000 if no climate policies are adopted, which could result in a temperature rise of 2.4 to 4.6 degrees Celsius above 1990 levels.
In addition, the researchers found that if average global emissions peak between 2020 and 2040, that may result in an eventual leveling off of temperatures at between 0.5 to 2.8 degrees Celsius above 1990 levels. Emission reduction scenarios the researchers considered mainly involved improved energy efficiency and use of new low-carbon energy technologies.
Professor Martin Manning of the Climate Change Research Institute, School of Government at Victoria University of Wellington comments:
“Detlef van Vuuren and colleagues have summarised results from six international research groups that have looked at options for limiting global warming due to greenhouse gases during the 21st century. Their bottom line is that, while it is still possible to avoid warming of more than 2 degrees (C) above pre-industrial temperatures, this will require sustained reductions in greenhouse gas emissions at the maximum rates considered plausible.
“The Intergovernmental Panel on Climate Change (IPCC) assessment of climate change science completed last year showed that if greenhouse gases and other human influences on climate had somehow been frozen at year 2000 levels, the Earth would have continued to warm by about 0.6 degrees (C) as the oceans caught up with the altered atmosphere. This is a committed warming due to lags in the physical climate system.
“The new study estimates that a further committed warming due to the inevitable lags in implementing the necessary technological and socio-economic changes on a global scale will be larger at about 0.8 degrees (C). When combined with the fact that year 2000 temperatures were about 0.5 degrees (C) warmer than pre-industrial levels, the numbers add up to mean that the world cannot afford to delay if we are to avoid the 2 degrees (C) warming that many governments regard as the tolerable maximum safe level of warming.
“The good news is that not only is the 2 degrees (C) warming target still possible, but that it appears to be achievable using current or foreseeable technologies while also allowing for steady growth in GDP per person. The highest costs associated with the most stringent greenhouse gas reductions have a net present value of 2 – 3% of future GDP and, while the authors did not estimate the benefits of the avoided climate change impacts against which this should be compared, a range of other studies have suggested that such benefits are larger than the costs of achieving them.
“The bad news is that not only will we all have to adapt to a significantly warmer world, but that long term projections of climate remain uncertain due to our lack of detailed knowledge of the physical and biological responses in such a world. Because of this, even if the international policy process can be mobilised quickly to aim for the 2 degrees (C) target, prudent risk management in areas that are more exposed to the effects of climate change will still need to plan for higher levels of warming.”
To talk to this expert or others about this issue, please contact the Science Media Centre on tel: 04 499 5476 or email: smc@sciencemediacentre.co.nz.
Notes to Editors
The Science Media Centre (SMC) is an independent source of expert comment and information for journalists covering science and technology in New Zealand. Our aim is to promote accurate, bias-free reporting on science and technology by helping the media work more closely with the scientific community. The SMC is an independent centre established by the Royal Society of New Zealand with funding from the Ministry of Research, Science and Technology. The views expressed in this Science Alert are those of the individuals and organisations indicated and do not reflect the views of the SMC or its employees. For further information about the centre, or to offer feedback, please email us at smc@sciencemediacentre.co.nz.