The most stringent emissions scenario in the study, led by the University of Reading’s Walker Institute, keeps global temperature rise below two degrees C and global greenhouse gas emissions peaking in 2016 and then reducing at five per cent per year until 2050. The two degree target is the focus of international climate negotiations, the latest round of which took place in Doha in December 2012. However, relatively little research has been done to quantify the worldwide benefits, in terms of avoided or reduced impacts, of the two degree target.
Of the impacts studied, crop productivity, flooding and energy for cooling are the areas that see the greatest benefit from emission reductions: global impacts in these areas are reduced by 40 to 65 per cent by 2100 if warming can be limited to two degrees. In contrast, the adverse impacts of climate change on water availability are only reduced by around 20 per cent when emission limitations are imposed. This is because even a small amount of warming can alter rainfall patterns sufficiently to reduce water availability.
Limiting emissions also has the effect of delaying climate change impacts by many decades. One example from the new research shows global productivity of spring wheat could drop by 20 per cent by the 2050s, but such a drop in yields is delayed until 2100 with stringent emission limits. Similar delays are seen in increased exposure to flood risk and rising energy demand for cooling.
Professor Nicholls, who led the coastal impacts aspect of the study, says: “Reducing greenhouse gas emissions clearly provides benefits in reducing impacts in many sectors. From a coastal perspective, long-term climate mitigation is important as some nations – especially developing nations or remote, small low-lying islands - cannot easily implement efficient protective measures. Mitigation does not avoid all impacts, but it reduces them to a level where protection and adaptation becomes much more feasible. Mitigation also gives the natural environment – such as wetlands - more time to respond naturally to rises in sea level.”
Secretary of State for Energy and Climate Change, Edward Davey, said “We can avoid many of the worst impacts of climate change if we work hard together to keep global emissions down. This research helps us quantify the benefits of limiting temperature rise to 2°C and underlines why it’s vital we stick with the UN climate change negotiations and secure a global legally binding deal by 2015.”
The new research provides the first comprehensive assessment of the benefits of limiting global greenhouse gas emissions. A range of impact indicators are considered including: flooding, water availability, crop productivity and energy for heating and cooling.