Climate is changing. But, questions such as, is climate change accelerating or is the climate change affecting some parts of Bangladesh but not in the UK and hence temperature rises 40 degree Celsius in Bangladesh but temperature in the UK at the same time 18 degree Celsius? Such questions divide the opinions and raise some doubt about climate change.

Since June 2023, every consecutive month has been the hottest on record. Sea surface temperature also stayed at a record higher since this time last year. This indicates that Earth's climate is warming. But the question raises that climate operates on the scale of decades not years. So, just interpreting 2023 climate change data has raised a schism in the climate science community.

A new study conducted by Oregon State University’s College of Earth, Ocean and Atmospheric Sciences (CEOAS) and the University of St Andrew’s School of Earth and Environmental Sciences (EES) suggests that carbon dioxide is increasing in the atmosphere ten times faster than it has in the last fifty thousand years. CEOAS team indicated, “Studying the past teaches us how today is different.

The rate of carbon dioxide change today really is unprecedented.” In a press release, St. Andrews team mentioned that the research identified the fastest rates of carbon dioxide rise ever observed, which is largely driven by human emissions.

Detailed analysis of chemicals in ancient Antarctic ice core carried out by an international team showed the impact of human carbon emission.

Scientists drill cores as deep as two miles in order to take samples of the ice, analyse trace chemicals and put together records of the climate of the past. Research revealed that the last ice age, which came to an end roughly ten thousand years ago, contained several periods during which carbon levels appeared to spike.

Using samples from the ice core of West Antarctica, the team found a pattern showing that the sharp increases in carbon dioxide occurred alongside cold intervals in the North Atlantic, which is known as the Heinrich event:

a natural phenomenon in which large groups of icebergs break off from the Laurentide Ice Sheet and traverse the Hudson Strait into the North Atlantic. First described by marine geologist Heinrich, they occurred during five of the last seven glacial periods over the past six hundred thousand years.

CEOAS teams suggest that Heinrich events are truly remarkable. This instigates a chain reaction that involves changes to the tropical monsoons and the Southern Hemisphere westerly winds and, as a result of that, large amounts of carbon dioxide are coming out of the oceans. St. Andrew’s EES team suggests, “These Heinrich Events kick off an astonishing sequence of rapid shifts in climate around the world.

They start with a weakening of the North Atlantic’s circulation system, which causes rapid cooling in northwest Europe, sea ice expansion from Scotland to New York, and disruption to tropical monsoons. They also change winds and circulation in the ocean around Antarctica, which belches out carbon dioxide.”

It is interesting to note that the Southern Ocean takes up part of carbon dioxide that we emit, but the evidence suggests that westerly winds integral to deep ocean circulation are also getting stronger, bringing about a quick release of carbon from the Southern Ocean. Previous studies have suggested that climate change will cause westerly winds to get stronger over the course of the next century.

If that happens, then the Southern Ocean’s ability to absorb human-generated carbon will be reduced.

Another scenario we come across in recent times. Researchers at the University of Reading have reported an increase in the rate of short-wave radiation from the sun penetrating Earth’s atmosphere since 2001. Reading University research group reported, “If we are increasing the amount of short-wave radiation that’s coming into the climate system, we would expect that to cause a warming.”

Please note that Shortwave radiation is thermal radiation in the optical spectrum, including visible, near-ultraviolet and near-infrared spectra.

There are some anomalies in the prediction from the regional climate model. Such models underestimate summer heat because they do not factor in more intense sunshine due to falling air pollution. It has been observed that regional climate models underestimate the actual warming by more than 1 degree Celsius. Besides that, there is another scenario that emerges from the El Nino event.

One of the major influences on our weather is the El Niño Standard Oscillation (ENSO). The ENSO is a change in the temperatures and weather in the Pacific Ocean around the equator.

It is split into three different phases – a neutral state, La Niña (a cooling state), and El Niño (a warming state). Typically, in the Pacific Ocean, water temperatures are higher around Australia and Asia, and cooler around the west coast of America. The prevalent winds in the ocean also run from east to west. This is the ENSO in its neutral state.  

But El Nino causes more disruption. In this event, the temperatures in the Pacific Ocean rise, particularly around the coast of South America. The prevailing winds across the Pacific also lessen, or in extreme cases can be reversed. This can have a big effect on the world’s weather patterns.

It can make some regions of the world more prone to drought and heatwaves, while others are more likely to see severe storms and flooding. Generally during an El Niño event, world temperatures rise. Though scientific schism also exists regarding this matter because some are sceptical that El Nino explains all of the global warming that we have observed in 2023.

Above all, research is underway to assess the cooling effect from volcanic eruptions and aerosol affect from shipping pollution in addition to what is happening naturally such as excessive short-wave radiation from the sun.

Also, when no El Nino event occurs and, at the same time, if surface temperature also decreases, then we would be able to get some hint that El Nino is responsible for the heatwave in Bangladesh and not in the UK at the same time. Until such time scientific schism about climate change will remain.
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The writer is a UK-based academic, advisor (Science & Environment), columnist and author