Earth is experiencing unprecedented heat waves, with record-breaking temperatures being observed. The University of Maine’s Climate Reanalyzer reported that Earth broke the record for its hottest day in 120,000 years three times in the past week. These extreme temperatures are expected to continue as El Niño intensifies, adding more heat to the Earth’s system.
The climate scientists are confident in these assertions based on observations showing that temperatures in the past decade have been the warmest since the 1800s.
Analysis of proxy data, such as tree rings and ice cores, indicates that Earth’s average temperature has not been this warm since the end of the ice age 20,000 years ago.
The current rate of warming has been unparalleled in the past 20,000 years, with Earth’s average temperature rising by 1.2 degrees Celsius (2 degrees Fahrenheit) since the Industrial Revolution. Astonishingly, humans are projected to cause the same amount of warming in just 200 years through burning fossil fuels and greenhouse gas emissions, which is 50 times faster than the natural warming rate after the last ice age.
According to studies, the period between 10,000 years ago and the present has experienced relatively stable temperatures, allowing human civilizations to thrive. However, if carbon emissions are not curbed, Earth is expected to warm by another degree by mid-century, similar to the temperatures during the last interglacial period 125,000 years ago. If emissions continue unabated, the world may experience the hottest temperatures in over one million years by the end of the century.
The heat waves are not limited to specific regions, but have become a global phenomenon. This year has already seen severe, record heatwaves roil places from Puerto Rico to Siberia to Spain, while blistering heat in Canada helped spur huge wildfires that blotted the skies above New York City and Washington with toxic smoke last week.
In the U.S., Texas and the southwest are enduring a searing heatwave, with over 120 million Americans under heat advisories, studies show.
The UK experienced its hottest June on record, surpassing the previous record by 0.9 degrees Celsius.
North Africa, the Middle East, and Asia are also witnessing unprecedented hot weather.
The European Center for Medium-Range Weather Forecasts declared June the hottest month globally. The trend of extreme heat has continued with the three hottest days recorded in the past week, according to Copernicus, the EU’s climate and weather service.
Oceans
The impact of rising temperatures is not limited to air temperature, but also affects the oceans. Record ocean temperatures have been observed this spring and summer, particularly in the North Atlantic, where surface water temperatures are at their highest levels ever recorded. This marine heatwave also contributes to above-average temperatures along the coasts of the UK.
Heatwaves in the Atlantic and Pacific oceans have led to the highest global sea surface temperatures recorded in April and May.
The U.S. National Oceanic and Atmospheric Administration (NOAA) confirming a second consecutive month of record high ocean surface temperatures in May. Excess heat in the oceans, which cover 70% of the globe’s surface, influences overall global temperatures, as well as warping fish populations, bleaching coral reefs and driving coastal sea level rises.
“The oceans have been warming steadily but we are now seeing record temperatures which is certainly alarming given we are expecting El Niño to strengthen,” said Ellen Bartow-Gillies, a climate scientist at NOAA. “That will undoubtedly have an impact on the rest of the world.”
Bartow-Gillies said NOAA had not yet processed its temperature data for June but that it appeared the elevated heat will continue this month, although El Niño will not be a major factor until later in the year. “We are off to a pretty warm start to the year, it’s not unprecedented, but we could be getting even warmer due to El Niño,” she said.
The warming of the seas contributes to higher air temperatures, as the excess heat trapped by greenhouse gases gets released into the atmosphere when brought to the surface by ocean currents like El Niño.
The exceptionally hot weather experienced reflects the long-known impacts of climate change. Greenhouse gas (GHG) emissions are continuing to rise, and the growth rate, although slightly slowed, remains significant. The higher the global temperature, the greater the risk of heat waves, which are now more frequent, hotter, and longer due to global warming.
The future beyond 2050 is uncertain due to the unpredictability in emissions reduction efforts and Earth’s system feedbacks to warming temperatures. Experts’ latest estimates suggest that Earth is on track to warm approximately 2.7 degrees Celsius by 2100 under current government policies on emissions. However, this projection relies on assumptions about government actions and emissions, and more significant warming is possible if emissions continue at current rates.
Tracking Breaches Of The 1.5⁰C Global Warming Threshold
Copernicus, the EU’s climate and weather service (https://climate.copernicus.eu/tracking-breaches-150c-global-warming-threshold) said:
Global-mean surface air temperatures for the first days of June 2023 were the highest in the ERA5 data record for early June by a substantial margin, following a May during which sea-surface temperatures were at unprecedented levels for the time of year.
Also in May, the World Meteorological Organization published a report highlighting a 66% likelihood that the annual average global temperature in 2023-2027 would be more than 1.5°C above pre-industrial levels for at least one year.
Copernicus raised the question:
So, did we in fact witness a rise in the global-mean temperature to over 1.5⁰C above the 1850-1900 level in early June?
The EU’s climate and weather service said:
Let’s take a closer look at what the ERA5 figures tell us, and how they are calculated.
In December 2015, the nations of the world adopted the Paris Agreement, under which they would pursue efforts to limit the rise in the climatological average global temperature to 1.5⁰C above pre-industrial levels. As it happens, a strong El Niño was close to its peak at the time, and it is now estimated that for a few days the global-mean temperature was more than 1.5⁰C higher than the pre-industrial temperature for the month. This was probably the first time this had occurred in the industrial era.
As the current El Niño continues to develop there is good reason to expect periods in the coming twelve months during which the global-mean air temperature again exceeds pre-industrial levels by more than 1.5⁰C. What’s more, according to the WMO report mentioned above, there is a 98% likelihood that at least one of the next five years, and the five-year period as a whole, will be the warmest on record, and a 32% chance that the five-year mean will exceed the 1.5°C threshold.
The global-mean temperature figures provided by ERA5 reveal remarkable global warmth in early June 2023. In the figure below, we can see that the global-mean temperature indeed breached the 1.5⁰C limit in the first week of June. However, it remains to be seen how often, for how long and by how much the limit is exceeded in the coming twelve months or so, as the current El Niño completes its cycle.
It must be stressed that the 1.5⁰C and 2⁰C limits set in the Paris Agreement are targets for the average temperature of the planet over the twenty or thirty-year periods typically used to define climate. The impacts of a warming climate nevertheless vary considerably with season and location, and passing the long-term global limits at any one time of year or any one place may not be of particular significance. However, as the global-mean temperature continues to rise and more frequently exceed the 1.5⁰C limit, the cumulative effects of the exceedances will become increasingly serious and must be carefully monitored to keep track of how rapidly we are closing in on the long-term thresholds.
The Data Are Clear
“The world has just experienced its warmest early June on record, following a month of May that was less than 0.1°C cooler than the warmest May on record. Monitoring our climate is more important than ever to determine how often and for how long global temperatures are exceeding the 1.5 degrees threshold. Every single fraction of a degree matters to avoid even more severe consequences of the climate crisis,” said Copernicus Climate Change Service (C3S) Deputy Director Samantha Burgess.
How do the early June 2023 temperatures fit into the historical record? This is not the first time that global temperature rises have exceeded the 1.5⁰C level.
(a) Global-mean temperature (⁰C) averaged for each day of ERA5 from 1 January 1940 to 11 June 2023, plotted as time series for each year, with years from 2015 onwards distinguished by colour. The dashed and dotted lines denote values that are respectively 1.5⁰C and 2⁰C above the 1850-1900 reference values taken to represent pre-industrial levels. (b) Global-mean temperatures for 2016, 2020 and parts of 2015 and 2023 expressed as differences (⁰C) from 1850-1900 levels.DATE:15th June 2023
Panel (a) above shows annual time series of daily ERA5 global-mean surface air temperatures from 1940 onwards. Levels that are estimated to be 1.5⁰C and 2⁰C above 1850-1900 reference levels are indicated. The first time in this time series where a monthly average appears above the 1.5⁰C level was in December 2015. Panel (b) complements the information in Panel (a) and shows more clearly the temperature differences for 2016, 2020 and parts of 2015 and 2023 as compared to 1850-1900 values. 2016 and 2020 are the two warmest calendar years in the data record, and the two years prior to 2023 with the most conspicuous occasional breaches of the 1.5⁰C limit.
Exceeding 1.5⁰C has typically occurred in the boreal winter and early spring, most notably in February and March 2016. This is the time of year when the rise in temperature since 1850-1900 has been largest. Seasonality is particularly evident over and close to the Arctic Ocean, where substantial winter warming of the atmosphere has occurred over regions where ice cover has been lower in recent years, and summer warming has been inhibited by the seasonal melting of sea ice, which keeps temperatures close to 0⁰C. Other factors also play a part but, regardless of cause, the larger warming in boreal winter and early spring makes exceedance of the limit more likely at this time of year, especially when temperatures have been temporarily enhanced by an El Niño. Conversely, the temperature limit is generally further from being exceeded in boreal summer. The warm period at the beginning of June 2023 is an exception.
El Niño Will Have Significant Heating Effect
Copernicus said that the first few days of the month even breached a 1.5C increase compared with pre-industrial times. This is probably the first time this has happened since industrialization, the agency said.
A report by The Guardian said on 15 Jun 2023:
Last week, NOAA said El Niño conditions are now present and will “gradually strengthen” into early next year.
Michael Mann, a climate scientist at the University of Pennsylvania, said human-caused warming will be exacerbated by an event that typically adds between 0.1C to 0.2C (0.18F to 0.36F) to the overall global temperature.
“The global surface temperature anomaly is at or near record levels right now, and 2023 will almost certainly be the warmest year on record,” said Mann. “That is likely to be true for just about every El Niño year in the future as well, as long as we continue to warm the planet with fossil fuel burning and carbon pollution.”
Mika Rantanen, a Finnish meteorologist, said that the spiking heat so far this month was “extraordinary” and that it was “pretty certain” it would result in a record warm June.
According to an update issued by NOAA on Wednesday, the world had its third warmest May in a 174-year temperature record last month, with North America and South America both having their hottest May ever recorded.
NOAA is more circumspect about the prospects of an annual heat record in 2023, placing the odds at about 12%, but has said it is almost certain the year will rank in the top 10 warmest and is very likely to be in the top five.
Regardless of whether 2023 ends up the hottest ever recorded, scientists caution that the escalating impacts of the climate crisis are now starkly evident and will not be slowed until greenhouse gas emissions are radically cut.
“Without stronger emission cuts, the changes we are seeing are just the start of the adverse impacts we can expect to see,” said Natalie Mahowald, an atmospheric scientist at Cornell University. “This year and the extreme events we have seen so far should serve as a warning.”
