What does global warming mean for Botswana and Namibia?

Wednesday, 10 October 2018 14:08 GMT

The sun sets over the Okavango Delta, Botswana, April 25, 2018. REUTERS/Mike Hutchings

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Even a 1.5 degree C rise in temperatures will bring more droughts and heatwaves, researchers warn

The release this week of the Intergovernmental Panel on Climate Change’s (IPCC) special report on global warming of 1.5 degrees Celsius above pre-industrial levels marks a critical point in climate negotiations.

Billed in the media as “life changing”, the report illustrates how crossing the ever-nearer threshold of 1.5C warming will affect the planet, and how difficult it will be to avoid overshooting this target.

The report takes a worldwide look at the growing impacts of climate change. But for hot, dry, water-stressed countries like Botswana and Namibia it’s important to understand how surpassing the 1.5C global limit will play out at the local level.

In these climate change “hotspots” - prone to droughts and floods -- local warming and drying will be greater than the global average. Even a 1.5C increase in global temperature will have severe local impacts, ushering in intensified and longer droughts and many more heatwaves.

Ironically, when rain does fall, it is expected to be much heavier, increasing the risk of heavy flooding within an overall drying climate.

The Paris Agreement’s goal of limiting global warming to well below 2 degrees Celsius, ideally 1.5C, by the turn of the century will be extremely challenging. To date, mitigation pledges by nations fall far short of what is needed, with global temperatures on track for warming of 3.2C by 2100.

If global emissions continue to increase, the 1.5C threshold could be breached as early as the next decade, and the 2C mark the decade after. This means there is an urgent need for countries like Botswana and Namibia to prepare and adapt.

SMALL HIKES, BIG CONSEQUENCES

What seem like small increments in global temperature can have serious local consequences. Our new analysis from the Adaptation at Scale in Semi-Arid Regions (ASSAR) project shows that for Botswana and Namibia 1.5C of global warming would lead to an average temperature rise in each country of 2.2C and 2C respectively. At 2C global warming, Botswana would warm by 2.8C, and Namibia by 2.7C.

Changes in rainfall are projected. At 1.5C of global warming, Botswana would receive 5 percent less annual rainfall, and Namibia 4 percent less. At 2C global warming, annual rainfall would drop by 9 percent in Botswana and by 7 percent in Namibia.

The impacts of higher global and local temperatures will be felt in sectors key to the prosperity of people and economies in these countries.

In a hotter, drier future there will be less domestic water available. For example, runoff in Botswana’s Limpopo river catchment is projected to decline by 26 percent at 1.5C global warming, and by 36 percent at 2C.

Agriculture is particularly vulnerable, with potential drops in crop yields and increased livestock losses.

Global warming will also affect human health. At 1.5C of global warming, Namibia and Botswana can expect roughly 20 more days of exposure to heat stress in a year. At 2C, in Namibia, this doubles to around 40 more days.

All of these impacts become even more severe above the 2C threshold.

URGENT ACTION

The implications of what the near future holds for these countries, which are already dealing with climate adaptation challenges, demand concerted action, both locally and internationally.

Leaders from countries such as Botswana and Namibia must continue pushing on the global stage for nations to make good on, and improve, their pledges to cut greenhouse gas emissions in line with the Paris Agreement.

Given the lack of ambition in emission reductions so far, and major energy and land-use transformations the IPCC report claims will be needed, highly exposed countries such as Namibia and Botswana need to anticipate and plan for quite rapid changes in local weather and climate characteristics.

The time for pilot adaptation projects and experiments is over. The moment to start mainstreaming climate resilience into public, private and community sectors has arrived.

Governments, scientists and development practitioners need to think longer term, to consider what overshooting the 1.5C and 2C targets really means for adaptation. At some stage, adaptation of these systems may not be enough, and complete transformations to new livelihoods that are suitable in a 2C+ world may be needed.

Mark New directs the African Climate and Development Initiative at the University of Cape Town and is a principal investigator in the Adaptation at Scale in Semi-Arid Regions (ASSAR) project. Brendon Bosworth is a communications officer with ASSAR, based at the University of Cape Town.