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New strategy needed to cut the rate of global warming in half by 2042 say top scientists


Fast action will also save lives, protect harvests and help meet Sustainable Development Goals

Washington, DC, May 5, 2017. Governments must urgently aim to cut the rate of global warming in half over the next 25 years, a group of leading climate scientists concludes today. Meeting this “near-term goal” would involve taking much more rapid action than is envisaged in the groundbreaking Paris Agreement, and require aggressively reducing emissions of short-lived climate pollutants along with long-lived carbon dioxide.

Writing in today's issue of Science, the scientists – members of the Scientific Advisory Panel of the Climate and Clean Air Coalition, which brings together 52 governments, 17 intergovernmental organizations, and 45 NGOs – say that achieving the ambitious goal of slowing warming by 0.5 degree Celsius over the next quarter of a century is “plausible” and would have “many potential benefits” in tackling poverty, improving health and avoiding damage to crops besides reducing climate change.

The Paris Agreement, struck in December 2015, sets a long-term goal of keeping the increase in temperatures to well below two degrees centigrade above pre-industrial levels over the course of the 21st century and aims to limit it to 1.5 degrees Celsius. But the scientists - from ten universities and leading bodies on four continents - conclude that, without a new strategy the warming increases are “likely to exceed 1.5 degrees C in the 2030s, and exceed two degrees C by mid-century”.

Such rapid temperature rises would also limit the ability of people – especially the poorest and most vulnerable - to adapt, increase damage to biodiversity which is particularly sensitive to the rate of climate change, and speed up damaging feedbacks, such as the way the melting of snow and ice darkens the Earth's surface, causing it to absorb more heat.

“Speed really matters in climate change,” said Durwood Zaelke, President of the Institute for Governance & Sustainable Development. “Fast action could make the difference between living in a safe climate and suffering from uncontrollable impacts, not least from self-amplifying feedback mechanisms that risk irreversible and potentially catastrophic effects”.

“The proposed near-term goal would help focus global action towards immediately available opportunities to avoid disaster,” said co-author Nathan Borgford-Parnell, an IGSD Senior Law Fellow.

The Science paper adds that the key to meeting the goal will be in reducing the emissions of short-term climate pollutants that together cause about half of global warming and are up to thousands of times more potent, pound for pound, than carbon dioxide. Cutting them would have particularly rapid results because they last only weeks to months in the atmosphere, compared to centuries for much of carbon dioxide emissions.

The new paper proposes cutting emissions of one of these short-lived pollutants, methane, by some 75 percent, and another – black carbon, or soot – by some 25 per cent, by around 2030, so as to reach the goal. And it also relies on eliminating high-warming hydrofluorocarbons (HFCs) through quickly ratifying and implementing an amendment to the Montreal Protocol to this end agreed in Kigali last year, which itself can avoid up to 0.5 Celsius by the end of the century.

The strategy would also save lives and crop harvests since black carbon kills some seven million people through air pollution each year, and methane gives rise to ground-level ozone which damages crops and health. The scientists say that it would also cut the cost of meeting the Paris targets and help to achieve the internationally agreed Sustainable Development Goals.

“If we do not implement near-term strategies and only focus on long-term goals we will miss the opportunity to achieve multiple benefits and reduce premature deaths, avoid millions of tonnes of reduced crop yield and avoid climate-related impacts that will be associated with rapid increases in temperature,” said Dr. Drew Shindell, Professor of Climate Science at Duke University and the paper's lead author.

“It matters because damages due to climate change are already upon us, affecting the health and livelihoods of those alive today and challenging our ability to meet the 2030 Sustainable Development Goals. It matters because the rate of warming in the near-term affects the rate of crop failure in developing countries, and the rate of sea-level rise -  and policies to slow the rate have dramatic effects for food security and air quality.”

Johan Kuylenstierna, Policy Director of the Stockholm Environment Institute, added: “Having a near-term goal that achieves benefits across multiple objectives and across multiple parts of the government can motivate action, focus effort and coordinate policy.”

Find the full paper here.