Climate Change and Extreme Events: An Update
Raghu
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THE UN World Meteorological Organisation (WMO) last month released its State of the Climate Report 2023, which not only confirms the fears of most observers that global warming has reached alarming levels, but also offers much evidence that climate change and its attendant impacts are advancing much faster than earlier thought.
RECORD-BREAKING YEAR
The WMO Report shows that “the year 2023 broke every single climate indicator.” The global average temperature in 2023 was 1.45 deg C ± 0.12 C above the 1850-1900 industrial era average. Readers would note that this is perilously close to the 1.5 C temperature rise limit set in the Paris Agreement (PA) and reiterated in several subsequent scientific reports of the Inter–governmental Panel on Climate Change (IPCC), beyond which climate change could reach threatening and possibly irreversible levels.
It comes as no surprise then that the atmospheric concentrations of greenhouse gases, chiefly carbon dioxide, methane and nitrous oxide, which are the primary cause behind global warming and climate change, were also at record highs. Carbon dioxide (CO2) concentration reached 417.9 ppm (parts per million), methane (CH4) 1923 ppb (parts per billion) and Nitrous oxide (N2O) 335.8 ppb, which are 154 per cent, 264 per cent and 154 per cent higher respectively than their pre-industrial levels, all three greenhouse gases (GHG) having very high rates of increase.
Although it is not used as a determinant metric any more, a CO2 atmospheric concentration of 420 ppm used to be considered the Rubicon that should not be crossed. Like temperature rise, atmospheric CO2 levels too are on the brink.
The WMO Report also shows that almost all major climate impacts have also worsened.
OCEANS
Sea levels not only continue to rise, but are rising far more rapidly than earlier, and at the highest rates recorded so far. Mean sea level has been rising at the rate of 4.77 mm per year during the past decade of 2014-23, compared to 2.13 mm/yr during 1993-2002. While heat waves on land have understandably drawn much attention since most of the population directly experiences them, the general public is less aware of marine heat waves (MHW) even though they affect people far more than they realise. Warming of the oceans has been one of the most consistently observed phenomena resulting from climate change. Oceans in fact absorb most of the excess heat generated by greenhouse gases (GHG). Increasing ocean temperatures affect global and regional weather patterns, have a major influence on sea currents which in turn affect the climate, and have huge impact on marine life and ecosystems and hence on humans dependent on them. At the present juncture, major coral bleaching events have been observed, which have widespread impacts on marine breeding grounds.
In 2023 itself, more severe and much longer-lasting MHW have been observed over large swathes of ocean, especially in the Mediterranean and the North Atlantic which witnessed temperatures of about 3C higher than the average. As expected, marine cold waves (MCW) declined in both occurrence and severity.
Ocean acidification too has reached record levels and is increasing at higher rates than earlier. Oceans annually absorb around one-third of carbon dioxide emitted which then reacts with seawater to produce acids. Ocean pH levels (a measure of acidity, with pH numbers indicating more acidity and higher pH values indicating more alkalinity) are now at record lows, having widespread impacts on marine life and ecosystems, with further impacts on food security
THE CRYOSPHERE
The cryosphere, meaning polar ice and ice-sheets, permanent snow cover and glaciers elsewhere, have been severely affected by climate change and are on the verge of triggering major shifts in global and regional climate. These often dramatic changes have the potential to affect hundreds of millions of people.
Arctic sea ice has been shrinking for years and, over the past decade, has been at its lowest since satellite recording began in 1979. The minimum area of Arctic ice recorded last year was 4.23 sq.km, a good 20 per cent lower than the long-term average over the past three decades. Antarctic ice, which has been causing increasing concern, reached a record low minimum of 1.79 sq.km while even its maximum area of close to 17 million sq.km was a substantial 1.5 million sq.km lower than the long-term average during 1991-2020.
Melting polar ice caps have far-reaching effects on climate and weather systems, marine ecosystems, bio-diversity and on the lives and livelihoods of people. Polar ice and adjoining snow-covered land being white reflect back solar heat sunlight through what is known as the albedo effect, and counters the heat absorbed by other regions. The more polar ice melts, the less solar heat is reflected back leading to greater warming. Polar jet stream or air current also gets affected by warmer air in the region, leading to more harsh winters in the polar and nearby regions. Melting polar ice adds to sea-level rise affecting islands and their people, coastal communities and others depending on marine resources and ecosystems. Melting polar ice has already opened up earlier permanently frozen polar regions to shipping and exploration for future extractive industries looking for fossil fuel and mineral deposits, with attendant disturbance of polar land and ocean ecosystems with potentially large-scale and dangerous environmental damage. Disruption of wildlife habitat in polar regions caused by melting polar ice and ice sheets already directly affects many species but also increases human-animal conflict causing much harm to both. And lastly, melting polar ice, ice sheets and permafrost also releases large quantities of formerly trapped dangerous methane thus accelerating climate change.
MELTING GLACIERS
The report also highlights rapid melting of glaciers over the previous decade, particularly in Western North America and Europe. Glaciers are also affected by the increasingly frequent and intense wildfires in the same region of North America and south-central Europe in particular, with Switzerland the worst affected. Warm summers and lower snowfall in these areas expose glacier ice which is darker than fresh or recently compressed snow, thus lowering the albedo and increasing warming. Wildfires depositing particulate matter on glaciers also have this effect. Readers in India will note that the well-known melting of glaciers in this country, especially in the Western Himalayas, have many very similar problems, but apparently of less severity than the American and European regions discussed here.
EXTREME EVENTS AND CONCLUSION
The WMO Report also covers the many extreme weather events during 2023 such as extreme rainfall, cyclonic storms, heat waves and wildfires, as well as drought, and their impact in terms of loss of life, displacement, food insecurity, health hazards and economic losses. The report notes that most such events took place in the Northern Hemisphere, notably in North America, the Mediterranean, Southern Europe, the Indian sub-continent hit by Cyclone Mocha, but also New Zealand. WMO notes that extreme events are increasing in frequency and severity.
This report underlines the grim picture with regard to climate change in its various inter-related dimensions. Of course, none of this is a surprise coming as it does so soon after the summation of scientific data under the Global Stocktake (GST) presented and approved at COP28 in Dubai. The GST also noted the large gap between the level of global emissions projected to 2030 and that required to restrict temperature to 1.5C. WMO has shown that the world is literally on the threshold of that landmark. All countries are now required to submit far more ambitious emissions reduction by mid-2025 for approval at COP30, with developed countries leading the way by committing to immediate and deep absolute emission cuts. India will inevitably come under pressure to also announce deep, economy-wide emissions reductions. India must get out of its present collusive relationship with the developed countries wherein each would go along with the other’s low- emissions reductions, and instead push the developed nations especially the US towards immediate deep cuts, while itself offering quite feasible cuts in sectors which its pledges have not touched so far.
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