The latest report from the United Nations’ Intergovernmental Panel on Climate Change, released Monday, has been heralded as a “code red” for action on rapidly warming global temperatures.
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Co-authored by hundreds of scientists from around the world, the report concludes that a significant amount of near-term warming is now unavoidable after a century of rising greenhouse gas emissions. It says action in the next few decades will be key to averting global catastrophe.
Here are five takeaways from the report, and what they mean for climate change in New Hampshire – from its coasts to its forests and rivers, to its ski slopes and cities.
1. It is “unequivocal” that human-caused greenhouse gas emissions have warmed the planet and raised sea levels in the past century, and especially in the past few decades.
While in 1990, the human influence on the climate was merely “suspected,” the IPCC says it is now “established fact.” New Hampshire and the rest of the world have seen at least about 1.8°F degree of warming and several inches of sea level rise over the past century.
The scientific community is more certain than ever that human activity – mainly oil and gas use – is directly responsible for these trends and other more regional changes, like more extreme rain and a diminished snow season in the Northeast.
2. Climate change has increased precipitation, extreme rainfall and river flooding in places like New Hampshire, and this trend will very likely continue. It’s still hard to say how droughts might increase here, but scientists do know that rainfall is getting more variable.
Local officials have said New Hampshire’s water infrastructure will need to get more resilient, with backups and redundancies, to handle greater swings in wet and dry conditions. Inconsistent rain is hard on farmers, plants and animals, and users of shallow wells. Warming weather also means less ice cover for lakes and rivers, and shorter dormant recovery periods of frozen ground.
The state has seen three of its most severe multi-year droughts on record, with the last one still currently lingering in Northern Coos County, in the past 20 years of concentrated warming.
3. We’re locked in for at least 2.7°F of warming in the next 30 years. But we can limit more warming in the decades that follow, and make our climate future less horrific for the world, by continuing to rapidly cut greenhouse gas emissions as much as possible.
By mid-century – when a child born today is 30, or around the time that many Gen-Xers and millennials may be retiring – New Hampshire summers will include many more days of extreme, dangerous heat – and heat waves – than residents are used to enduring. The IPCC says northern New England and Eastern Canada are getting hotter faster than much of the rest of the world.
Without drastic cuts to emissions, scientists say a nearly unimaginable future as much as 4°F warmer is possible by the end of the century – when today’s kids are in old age. This would prompt the greatest uptick in disruptive mass migration and routine deadly extreme weather.
4. Sea levels are “virtually certain” to rise at least 1 to 2 feet in the next 80 years even if the world can drastically lower its greenhouse gas emissions. Ocean acidification and marine heat waves will also continue the increases they’ve seen in the past century.
Many neighborhoods on the back marshes of Hampton and Rye will be flooded with ocean water around the clock by the end of the 21st century. The ocean will begin to encroach on Route 1A, state parks like Rye Harbor and tidal parts of Portsmouth.
Many more areas on the Seacoast will flood multiple times a month during high tides, raising questions for real estate development and infrastructure. Ocean warming and acidification will also reshape the fisheries on which the region relies, while threatening marine ecosystems.
5. The report says every single ton of carbon emissions counts when it comes to driving global warming – there’s a “near-linear relationship” between added emissions and added heat. More warming means more extreme changes in weather, and the hotter it gets, the less carbon will be able to be absorbed by our oceans, wetlands, grasslands and forests.
State-level critics of climate action have argued in the past that New Hampshire’s role in global carbon emissions is too small to merit changing our behavior. But the U.S. remains one of the top emitters in the world, and New Hampshire is part of a regionalized energy system – meaning change here has ripple effects beyond state lines, along with local economic and health benefits.
This report suggests that every person, and especially large governments and businesses, can contribute measurably to averting the worst possible climate outcome for the planet, beginning later this century and stretching thousands of years into the future.
Further reading:
- WBUR: 'Weather Whiplash' And Other Takeaways For Boston From The IPCC Report
- NYTimes: A Hotter Future Is Certain, Climate Panel Warns. But How Hot Is Up to Us.
- IPCC Interactive Atlas – explore warming scenarios and climate changes by region
