This May is the hottest May ever. In fact, each of the past 12 months has set a new warming record for that particular month, Europe’s Copernicus Climate Change Service (C3S) said last week.
The average global temperature last month was 1.5 degrees Celsius above the estimated May average for the pre-industrial period 1850-1900. For the 12-month period (June 2023 – May 2024), the average temperature was 1.63°C above the 1850–1900 average.
The World Meteorological Organization (WMO), in a separate report released on June 6, said there is an 80% chance that at least one calendar year between 2024 and 2028 will see its average temperature rise by more than 1.5 degrees Celsius above pre-industrial levels. For the first time in history. A year ago, the WMO predicted a 66% chance.
While these facts are alarming, they do not indicate that the world is going to exceed the commonly talked about 1.5°C temperature limit. That range represents warming over a long period of time, typically considering an average of two or three decades.
What is the 1.5°C limit?
In 2015, 195 countries signed the Paris Agreement, which pledged to limit global temperatures to “well below” 2 degrees Celsius above pre-industrial levels by the end of the century. It also said countries are aiming to limit warming to a safe limit of 1.5 degrees Celsius.
Although the agreement does not specify a specific pre-industrial period, climate scientists generally consider 1850 to 1900 as a baseline because it is the earliest period with reliable, global measurements.
The Industrial Revolution began in England in the mid-1700s. Nevertheless, a reliable baseline for measuring rising temperatures today is critical.
Why 1.5 degrees Celsius?
The safe 1.5°C threshold was chosen based on a fact-finding report, which found that exceeding the threshold would lead to “some regions and vulnerable ecosystems” facing increased risks over long, decades.
The 1.5°C “safety line” is set to ensure that the world avoids the catastrophic and irreversible adverse effects of climate change, which would begin to emerge once average temperatures rise 2°C above pre-industrial levels. For some regions, even a small spike can be catastrophic.
What happens if the threshold is crossed?
The 1.5°C threshold is not a light switch that, if turned on, will trigger a climate catastrophe.
If this threshold is breached over a long period of time, the impact of climate change, such as sea level rise, severe floods and droughts, and wildfires, will significantly increase and accelerate.
Speaking to MIT News, Sergey Baltsev, deputy director of the Joint Program on Science and Policy of Global Change at the Massachusetts Institute of Technology, said, “For example, if the temperature increase is 1.51 degrees Celsius, the science does not tell us. That would definitely be the end of the world.
Likewise, a 1.49 degree rise in temperature does not mean we will eliminate all impacts of climate change. “Known: Low target for temperature increase, low risks of climate impacts.”
The world is already seeing these effects to some extent. For example, extreme heat in northern and central India in late May saw temperatures of 50°C in Delhi and Rajasthan, nearly 1.5°C warmer than past heat waves. The heat wave is said to have caused hundreds of deaths and may also have contributed to the rise in global temperatures.
In April, the US National Oceanic and Atmospheric Administration (NOAA) said the fourth global mass coral bleaching event was triggered by abnormally high ocean temperatures. This could affect marine life and the livelihoods of millions of people who rely on reefs for food, jobs and coastal protection.
Last year, a report found that five major climate tipping points are already at risk of being crossed due to warming. Climate tipping points are critical thresholds beyond which a natural system can move to a completely different state. They cause irreversible damage to the planet, including global warming.
Scientists have identified many of these tipping points across the Earth, falling into three broad categories: the cryosphere (for example, the melting of the Greenland ice sheet), the ocean-atmosphere (changes in water temperature), and the biosphere (the death of coral reefs).
How can the world be at the door?
2023 was the hottest calendar year on record. The WMO reports that global average temperatures have reached 1.45 degrees Celsius above pre-industrial levels. But the unusually high temperatures were due to the onset of El Niño, an unusual warming of surface waters in the equatorial Pacific Ocean. This weather pattern is known to lead to record breaking surface and ocean temperatures in some parts of the world.
El Nino has now peaked and is likely to transition to a cooler La Nina in the coming months.
Nevertheless, the world is likely to temporarily exceed the 1.5°C limit in the next five years. A recent WMO report found that each year between 2024 and 2028 will be between 1.1°C and 1.9°C higher than the pre-industrial average.
The only sure way to stay on the threshold is to immediately and aggressively limit emissions of heat-trapping greenhouse gases (GHG).
To do this, the world must stop burning fossil fuels like coal, oil and gas, which release GHGs into the atmosphere. So far, countries have failed to make a significant impact in this regard.
By 2023, GHG levels in the atmosphere will reach historic highs. Carbon dioxide, the most anthropogenically produced GHG, rose by 2023 to the third-highest level in 65 years, according to NOAA.
As UN Secretary-General Antonio Guterres said on June 5: “We are playing Russian chicken with our planet… We need an exit from the highway to climate hell, and the truth is that we are in control of the wheel.
