Monday, January 24

Climate change has already affected southern Africa. This is how we know

Many people still think of climate change as a phenomenon that we will only face in the distant future. Perhaps this is partly because climate change projections for rising temperatures and extreme weather events are tied to future dates: 2030, 2050, or 2100, for example.

But it is important to realize that we are already experiencing climate change and have been for some time. Over the past century, global temperatures have risen by about 1 ° C. The rise in sea level is already from to affect certain low-lying coastal communities. The world is experiencing extreme more frequent and intense weather events.

The Intergovernmental Panel on Climate Change (IPCC) 6th Assessment Report: Physical Sciences Base, published in September 2021, contains a comprehensive, and largely gloomy, assessment of the state of recorded and projected global climate change. The IPCC is the United Nations body for the assessment of science related to climate change: a group of expert scientists from around the world, who write scientific reports on the state of the Earth’s climate and future projections of climate change .

Its latest report compiles research from 1,400 articles and will serve as an important reference document for the COP26 meeting in Glasgow, Scotland, from October 31 to November 12. It is there that science becomes politics.

This policy is fundamental for the whole world and urgent for southern Africa, which is particularly vulnerable to climatic changes. The region has already been experiencing faster climate changes and impacts that they are more severe than the world average. It also struggles with low adaptive capacity: there is little capital available to invest in protective measures against future climate threats and immediate human rights needs that are very urgent for a large proportion of the population.

The reality that southern Africa is in the midst of a climate emergency cannot be avoided. By identifying trends in the frequency of climate events and their intensity over a period of decades, and exploring related changes in biological systems in light of this, it is easy to see that the region has already been shaken by climate change. and related effects.

An extreme temperature rise

Extreme temperature events can be defined by maximum temperature, deviation from norm, or time of temperatures above threshold. A number of indices have been developed by the World Meteorological Organization to identify and quantify these extreme temperature events.

Warm events, when they meet specific criteria, are called heat waves. These are particularly dangerous for people, animals and plants, and are a direct cause of death.

In southern Africa, there has been a increased severity and frequency of heat wave events over recent decades.

Interestingly, for some locations, there have also been increase in the frequency of extreme cold events.

While this is not a characteristic of global warming, it is induced by changes in regional weather patterns, such as the number of cold fronts moving over South Africa.

Severe drought

Drought is defined as a significant and prolonged deviation from average rainfall totals. The most severe and best-known drought in southern Africa in recent years was the “Day zero” crisis in Cape Town. While increased water pressure in Cape Town played a role in this, a long-term poleward shift in westerly winds with winter rains bringing cold fronts and rain to Cape Town. Cabo during the winter months was a significant factor. taxpayer to this drought.

In general, southern Africa is also sensitive to El Niño-induced droughts. El Niño refers to warmer-than-usual conditions in the eastern Pacific that persist for a couple of months to years, driven by a weakening of the trade winds and a resulting reduction in the influx of cooler water to the sea surface. right next to South America. This was the cause of the Drought 2015-2016 in South Africa’s Kruger Park, resulting in the drying up of the watering holes, and the widely publicized hippo death and subsequent sacrifice of other large mammals.

High intensity tropical cyclones

The southern subcontinent of Africa is relatively well protected from tropical cyclones by the island of Madagascar. However, some tropical cyclones form in the Mozambique Channel, and occasionally some tropical cyclones move through Madagascar. These storms can, and do, as seen more recently with tropical cyclones Idai, Kenneth and Eloise, make landfall in Mozambique.

In recent decades, tropical cyclones in the southwestern Indian Ocean have increased in intensity; the first category 5 tropical cyclone for the sub-ocean basin was recorded in 1994.

Tropical Cyclone Idai, which edged in intensity between categories 3 and 4 upon making landfall, provides clear evidence of the damage caused by high intensity tropical cyclones in populated areas.

There’s also evidence that tropical cyclones have expanded their range poleward in recent decades, affecting a larger region of southern Africa.

Changes at the time of phenological events.

In addition to the weather we experience due to climate change itself, climate change also has an impact on biological systems. Phenology, which refers to the timing of biological events that repeat annually, is one of the most sensitive bioindicators of climate change.

In South Africa, scientists have made progress in the Moment of apple and pear flowering. in the southwestern Cape, and from Jacaranda bloom in the Gauteng city region. Warmer sea surface temperatures have also led to a delay in the sardine race along the southern coast of KwaZulu-Natal.

These changes have an impact on agriculture and tourism, but more importantly, they show that climate change is having an effect on the natural environment. These changes over time cannot continue indefinitely. Plants and animals have thresholds beyond which the stresses of climate change will cause at least local extinction.

The outlook looks bleak, but with mitigation and adaptation strategies and policies promoted through, among other processes, COP26, southern Africa can reduce the impacts of climate change on local livelihoods. At this stage, it is important to invest in adaptation to reduce the impacts of climate change and to do everything possible to reduce our dependence on carbon to curb climate change.The conversation

Jennifer Fitchett, Associate Professor of Physical Geography, University of the Witwatersrand.

This article is republished from The conversation under a Creative Commons license. Read the Original article.

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