Reports

Downscaled and Bias-adjusted Climate Projections for Afghanistan

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Summary and Key Impacts

Climate scenario analysis

• Historical climate datasets and an ensemble of climate projections have been downscaled and bias-adjusted to enable analysis of climate-driven hazards and risks to ecosystems, wildlife, hydrology, and communities across Afghanistan and in portions of neighboring countries.

Overview of the changing climate

• Climate model projections indicate that climate change will impact a range of sectors and alter the bioclimatic conditions across Afghanistan. Climate-related hazards will also shift, as critical variables such as precipitation (total and intensity), temperatures, extreme heat, soil moisture, snow, and permafrost change over time.
• The balance of changes across average and extreme climate conditions suggest disruptive pressures on society and natural ecosystems, which are important to recognize in current and future planning for Afghanistan.
• As future climate is likely to be different from past and current conditions, incorporating a range of possible projections in planning and decision-making is essential to minimize impacts and build resilience. A range of results is provided in this report by using two climate change scenarios, RCP2.6 (a low emissions pathway) and RCP8.5 (a high emissions pathway), accounting for uncertainty by examining eight separate downscaled climate models.

Projected mean temperature changes

• Projected warming is uniformly higher under the higher emissions RCP8.5 scenario compared to a lower emissions (higher mitigation) RCP2.6 scenario.
• RCP2.6 has a temperature peak in the 2050s and then declines slightly by the 2080s due to a substantial decrease in greenhouse gas concentrations under this pathway. By end century, temperatures are projected to increase by approximately 1.0-1.5°C compared to the recent past.
• Warming under RCP8.5 continues throughout the 21^st century, with accelerated warming between mid-century and end-century, resulting in an average temperature increase of approximately 4-6°C.
• Warming trends generally shift current temperature zones to higher elevations and lengthen the warmer seasons of the year.
• Warming is highest in the central portions of the country, in areas such as Bamyan, Ghor, Wardak and Daykundi provinces. Warming is lowest in the periphery of the country, in provinces such as Kunduz, Jawzjan and Nimroz.

Projected total precipitation changes

• Projected precipitation changes vary widely across the country, with some regions becoming drier and others becoming wetter by end century. The projected magnitude of changes is much greater under RCP8.5 compared to RCP2.6, although uncertainty across climate projections also increases. As with temperature projections, differences under RCP2.6 peak by mid-century, before returning closer to baseline by end-century; differences under RCP8.5 accelerate after mid-century, making those projections diverge widely from RCP2.6 by end-century.
• Under RCP 2.6 by end-century, the largest decreases in precipitation are ~30 mm, in portions of provinces including Zabul and Kabul. The largest increases are ~60 mm, in portions of Kunar and Badakhshan provinces.
• Under RCP 8.5 by end-century, decreases of ~200 mm are projected to occur in portions of Kabul and Kunar provinces (the latter of which has among the largest differences in projections under RCP2.6 and RCP8.5). On the other hand, portions of Badakhshan province are expected to experience increases of up to 100 mm.

Projected changes in natural hazards

• Extreme heat: The country is expected to experience ~0-15 extra days of extreme heat by end-century under RCP2.6, and ~0-60 extra days of extreme heat by end-century under RCP8.5. The spatial variation is pronounced. Generally, the coldest parts of the country such as eastern Badakhshan have the least risk; the warmest parts of the country such as Nimroz province have intermediate risk; and the portions of the country with intermediate temperatures such as Paktika and Khost provinces have the highest risk.
• Extreme precipitation: The frequency of extreme precipitation events is expected to increase in some areas and decrease in others, with the magnitude of the change depending on the threshold for considering a precipitation event to be extreme. Using 20 millimeters in a day as an illustrative threshold, northeastern provinces such as Badakhshan and Panjshir are expected to experience up to 5 more events per year compared to baseline by end-century under RCP8.5. On the other hand, provinces such as Laghman and Kunar are expected to experience 2-3 fewer events per year under the same scenario.
• Snow cover: The number of days per year with snow will decline across the entire country by mid-century, even under RCP2.6, and will not recover to baseline by end-century. Declines are much larger under RCP8.5 (up to 80 fewer days per year in provinces such as Ghazni); generally, the warmest parts of the country and the coolest parts of the country have the lowest projected changes, while areas of intermediate temperature (broadly the central provinces) have the largest projected difference.
• Soil moisture drought: Under RCP2.6, the frequency of 1-in-10-year soil moisture droughts is expected to decrease across the entire country using baseline thresholds for drought events, with the exception of portions of a few provinces such as Kunar and Faryab. Generally, the increase in drought risk for those places is of far lower magnitude than the decrease in drought risk for much of the rest of the country, with the biggest decreases in risk in southeastern provinces such as Zabul and Paktika. However, under RCP8.5, by end-century, several parts of the country will see significant increases in drought risk, such as Kunar, Khost and Nangarhar provinces.
• Growing season length: Growing season length will increase across the country, in line with the increased temperatures across the country. As with temperature, the largest increases will occur under RCP8.5 and by end-century. The warmest provinces, such as Nimroz, will see little to no increase as the baseline growing season spans virtually the entire year. The largest increases in growing season length are projected to occur in provinces such as Kapisa, Panjshir and Paktya, with those increases being up to 60 days by mid-century under RCP8.5.