This Christmas, the Arctic had a heatwave, scoring record high temperatures, even in the dark. A chunk of ice the size of the United Kingdom thawed in the warmth.
On the other side of the planet, a huge fracture in Antarctica’s ice shelf widened suddenly in December. Long term, the whole ice shelf will probably break up.
An ominous threshold is being reached, just as the very “old economy” Donald Trump, sworn to uphold climate denial and fossil fuel supremacy, is about to take control of the United States presidency.
2016 was the third year in a row that global temperature records were set, while ice coverage at both poles reached record lows. Records are being set at an accelerating pace. The warming effect of ice melting is self-reinforcing. The more ice that melts, the more ocean is exposed, the more water vapour there is. Water vapour acts as a greenhouse gas, trapping heat.
There had been some hope in the idea of a “pause” in global warming from 1998 to 2013, but a recent study of oceanic temperatures have demonstrated that this was a forlorn hope. The consequences of the changes that are already being recorded are quite familiar by now: increased droughts and flooding, the loss of species, and more volatile weather.
These effects are likely to become far worse. Crop yields will diminish. A review of 130 studies suggests that one in six species faces extinction. A review of over 600 studies suggests that the warming of oceanic waters will cause “species collapse from the top of the food chain down”.
In fact, it is probably worse than we think. Most of our assumptions have been based on the expectation of incremental change, with sea levels rising by centimetres in the next hundred years or so. A recent report by the Intergovernmental Panel on Climate Change has global sea levels rising at less than a metre by 2100 on the most pessimistic estimate.
This is based upon 20th-century patterns: global sea levels rose about 20cm from 1870 to the turn of the millennium. The idea that such linear trends would continue was contested by James Hansen of NASA in a 2006 report, which noted that geological evidence showed that beyond a certain threshold, sea levels can react abruptly to temperature changes, rising by metres rather than centimetres. Land mass supporting huge population centres would be submerged. The same research team recently published evidence suggesting that an increase in pre-industrial temperatures of just 2 degrees would have wildly abrupt, uneven effects, raising sea levels by several metres within 50 to 150 years. The American Association for the Advancement of Science expects “abrupt, unpredictable and potentially irreversible changes that have massively disruptive and large-scale impacts”. George Marshall, in his important book on climate denial, Don’t Even Think About It, writes: “Scientists, who are, as a group, extremely wary of exaggeration, nonetheless keep using the same word: catastrophe.”
Recent climate changes were stored up during a period in which governments generally agreed with climate science. Why did they do so little? Some things did change. After years of pursuing unavailing market-based solutions. such as carbon trading schemes – which quickly became a booming global industry – governments committed to keeping temperatures “well below” 2 degrees above pre-industrial levels at the Paris Accords.
Unfortunately, the means they pledged to achieve this would result in a 3-degree global temperature rise – a disastrous increase.
Unfortunately, matters are set to get worse. Donald Trump is about to be sworn in as president of the United States, and will appoint a climate denier as head of the Environment Protection Agency (abridged).
The author is an author and broadcaster based in London.
Source : Al Jazeera