Paris: Scientists monitoring Earth’s climate and environment have delivered a cascade of grim news in 2017, adding to the urgency of UN talks in Bonn next week tasked with ramping up efforts to tame global warming.
Earth’s average surface temperature last year was a record 1.1 degree Celsius (1.98 Fahrenheit) above the preindustrial era.
Our planet’s rising fever is caused by the accumulation of heat-trapping greenhouse gases in the atmosphere, especially carbon dioxide (CO2) cast off when fossil fuels are burned to produce energy.
Sixteen of the hottest years on record have occurred since the start of the 21st century.
The 196-nation Paris Agreement calls on humanity to block the rise in temperature at “well below” 2.0 C (3.6 F) compared to pre-industrial levels, and to consider setting the cap at 1.5 C.
The atmospheric concentration of carbon dioxide (CO2) reached an average of 403.3 parts per million (ppm) in 2016, the highest level in at least 800,000 years.
Last month, CO2 — three-quarters of greenhouse gas emissions — hit nearly 407 ppm. Prior to industrialisation, the global average hovered at about 280 ppm.
Concentrations of the second-most important greenhouse gases — methane (CH4) — have also risen sharply over the last decade, driven by leakage from the gas industry’s fracking boom, and growth in global livestock.
Many climate scientists argue that capping CO2 at 450 ppm gives us a fighting chance of staying under the 2 C threshold. Others say that the limit for a “climate-safe” world is much lower, around 350 ppm.
