Greenhouse gas cuts must start right away and continue after 2030
The deal currently on the table at the upcoming Paris climate talks would be a big step toward limiting global warming at or near 2 degrees Celsius — deemed a critical environmental threshold by climate scientists.
But reaching that target will require additional commitments to cut greenhouse gas emissions beyond 2025, according to a new study that took a close look at the pledges made by individual countries to reduce their emissions.
Published in Science, the study shows that, if implemented and followed by measures of equal or greater ambition, the Paris pledges can work. Leading up to the Paris climate summit, many countries have announced the contributions that they are willing to make to combat global climate change.
Examples of these commitments include the United States’ vow to reduce emissions in 2025 by 26-28 percent of 2005 levels and China’s pledge to peak emissions by 2030 and increase its share of non-fossil fuels in primary energy consumption to around 20 percent.
In the study, the scientists tallied up these INDCs and simulated the range of temperature outcomes the resulting emissions would bring in 2100 under different assumptions about possible emissions reductions beyond 2030.
“We wanted to know how the commitments would play out from a risk management perspective,” said economist Allen Fawcett of the U.S. Environmental Protection Agency, the lead author of the study. “We analyzed not only what the commitments would achieve over the next ten to fifteen years, but also how they might lay a foundation for the future.”
“It’s not just about 2 degrees,” said Gokul Iyer, the study’s lead scientist at the Joint Global Change Research Institute, a collaboration between the Department of Energy’s Pacific Northwest National Laboratory and the University of Maryland. “It is also important to understand what the INDCs imply for the worst levels of climate change.”
Immediate action to meet the goals set in Paris is crucial. If countries don’t act or delay until 2030, there’s little hope of capping warming at 2 degrees Celsius. But making immediate cuts and following up with more abatement greatly reduces the odds that warming exceeds 4 degrees. The extent to which the odds are improved depends on how much emissions limits are tightened in future pledges after 2030.
“Long-term temperature outcomes critically hinge on emissions reduction efforts beyond 2030,” said Iyer. “If countries implement their INDCs through 2030 and ramp up efforts beyond 2030, we’ll have a much better chance of avoiding extreme warming and keeping temperature change below 2 degrees Celsius. It’s important to know that the INDCs are a stepping stone to what we can do in the future.”