So you’ve been wondering what to recommend to your open-minded friends who want a readable but authoritative introduction to climate change, one which answers their key questions. Look no further! The US National Academy of Sciences and the U.K. Royal Society have achieved a breakthrough in readability with their new report, “Climate Change: Evidence & Causes.” Group reports by leading climate scientists are notoriously hard to read, such as the opaque-as-squid-ink IPCC report from September. But the Academy and Society shrewdly break the mold for climate reports by starting with a Climate Change Q&A — and by beginning each answer with a short, non-technical response: How do scientists know that recent climate change is largely caused by human activities? Scientists know that recent climate change is largely caused by human activities from an understanding of basic physics, comparing observations with models, and fingerprinting the detailed patterns of climate change caused by different human and natural influences. See, no biggie. Here’s another: Climate is always changing. Why is climate change of concern now? All major climate changes, including natural ones, are disruptive. Past climate changes led to extinction of many species, population migrations, and pronounced changes in the land surface and ocean circulation. The speed of the current climate change is faster than most of the past events, making it more difficult for human societies and the natural world to adapt. The more detailed answer goes on to note: Recent estimates of the increase in global average temperature since the end of the last ice age are 4 to 5 °C (7 to 9 °F). That change occurred over a period of about 7,000 years, starting 18,000 years ago…. If the rise in CO2 continues unchecked, warming of the same magnitude as the increase out of the ice age can be expected by the end of this century or soon after. This speed of warming is more than ten times that at the end of an ice age, the fastest known natural sustained change on a global scale. One might add that 18,000 years ago, there weren’t 7 billion people who had made a decision about where to live on the basis of a what had been relatively stable climate, sea levels, rain-fall patterns, and the like. By mid-century we’ll have 9 billion people on Earth, and, with unchecked CO2 emissions, a large fraction of those will simply be living in places that can’t sustain their population much longer. How confident are scientists that Earth will warm further over the coming century? Very confident. If emissions continue on their present trajectory, without either technological or regulatory abatement, then warming of 2.6 to 4.8 °C (4.7 to 8.6 °F) in addition to that which has already occurred would be expected by the end of the 21st century. Since we’ve already warmed about 1.5°F, that means scientists are very confident that if carbon pollution continues unchecked, we will warm 6 to 10 °F globally from preindustrial levels by century’s end. My only complaint is that the report doesn’t spell out in more detail some of the more serious consequences of that level of warming, but that is typical for staid, consensus-oriented bodies like the National Academy and Royal Society. Indeed, given that, what they have done in this very readable report is downright alarmist. As climatologist Lonnie Thompson explained back in 2010: Climatologists, like other scientists, tend to be a stolid group. We are not given to theatrical rantings about falling skies. Most of us are far more comfortable in our laboratories or gathering data in the field than we are giving interviews to journalists or speaking before Congressional committees. Why then are climatologists speaking out about the dangers of global warming? The answer is that virtually all of us are now convinced that global warming poses a clear and present danger to civilization. The post National Academy Of Sciences Delivers Highly Readable Climate Change Warning appeared first on ThinkProgress.
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