Kathmandu. The temperature in the world has increased a lot. Not only are we seeing record temperatures, but records are being broken by a wide margin. For example, early September global-average temperatures were found to be 1.7 degrees Celsius above pre-industrial levels. This is an incredible 0.5 degrees Celsius higher than the previous record. So why is the world warming so incredibly? And what does this mean for maintaining our Paris Agreement goals? Six factors are presented here.
1- El Nino refers to the sea surface temperature, or average sea surface temperature, in the central and eastern tropical Pacific Ocean. El Nino is believed to be one of the reasons for the extraordinary heat. During El Nino we see surface ocean temperatures in many tropical Pacific Oceans. This summer and the effects of El Niño in other parts of the world, the global average temperature has increased by about 0.1 to 0.2 degrees Celsius. We’ve just come out of a triple La Niña, which slightly lowered global average temperatures, and let’s not forget the fact that this is the first major El Niño in eight years, we’re seeing unusually high temperatures at the moment. Still, El Niño alone is not enough to explain the world’s extreme temperatures.
2- Air pollution caused by human activities cools the planet and affects the temperature caused by human greenhouse gas emissions. Efforts have been made to reduce this pollution, with an international agreement to reduce sulfur dioxide emissions from the global shipping industry in 2020. Current analysis shows that the impact of the 2020 shipping agreement is associated with an additional 0.05°C temperature increase by 2050.
3- If increase in solar activity and decrease in pollution level means that more energy of the sun reaches the surface of the earth, the amount of energy emitted by the sun is variable. There are different solar cycles, but the 11-year cycle is the most relevant to today’s climate. The Sun is becoming more active since the minimum in the second half of 2019. It is contributing to global warming to a small extent. Overall, increased solar activity is said to be contributing one hundredth of the maximum to current global warming.
4- On January 15, 2022, the underwater Hanga Tonga-Hanga Hapai volcano in the South Pacific erupted, releasing large amounts of water vapor into the upper atmosphere. Water vapor is a greenhouse gas, so increasing its concentration in the atmosphere increases the greenhouse effect. Although the eruption happened almost two years ago, it is still affecting the planet.
5- Unfortunately, even without factors like El Niño or major changes in pollution, we still see variability in global temperatures up to a year. One of the reasons for such extreme weather this September was probably that the weather system was in the right place to warm the land surface. When we have persistent high pressure systems over land, as has recently occurred in places like Western Europe and Australia, we see increased local temperatures and unseasonably warm conditions. Because it takes more energy to heat the water and move the ocean around, we don’t see as fast a response in ocean temperature as when we have a high pressure system. Continued ocean warming and climate systems that warm much of the land also contribute to global-average temperatures.
6- Climate Change Human-caused climate change is the largest contributor to the overall +1.7°C global temperature anomaly. Overall, humanity’s impact on climate is about 1.2 degrees Celsius of global warming. Record-high rates of greenhouse gas emissions mean we should expect global warming to accelerate as well. While humanity’s greenhouse gas emissions explain the observed trends in September temperatures over several decades, they do not explain the large differences between last September (when the greenhouse effect was nearly as strong as today) and September 2023. Much of the difference between this year and last comes from the switch from La Nina to El Niño and the right weather system in the right place at the right time.
A combination of climate change and other factors has caused us to experience alarmingly high temperatures. These anomalies may appear above the 1.5°C global warming level outlined in the Paris Agreement, but this is not about individual summer months, but about keeping long-term global warming at a low level. But we are seeing the effects of climate change more clearly. Rich countries emit the largest proportion of greenhouse gases, so the most vulnerable people suffer the greatest impact. Humanity must accelerate its path to net zero to prevent further record-breaking global warming and catastrophic extreme events.
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