Category Archives: precipitation

Projected longer dry spells under climate change occur during dry seasons

precipitation, projections

The latest Intergovernmental Panel on Climate Change (IPCC) report states that the global water cycle will intensify with continued global warming. This means fewer rainy days, but with more intense rain over many land regions, and more variability generally. More dry days and longer dry spells have the potential to lead to negative impacts on crop yields and food security, as reductions in water availability limit crop growth. The impacts on crops also depend on the timing of these longer dry spells in the annual cycle and future delays in the wet season are also reported in the IPCC report and by my previous research.

Guest post by Caroline Wainwright
Continue reading Projected longer dry spells under climate change occur during dry seasons →

Changing wet and dry seasons

extremes, precipitation

The fickle nature of weather patterns is ultimately responsible for the where and when of tropical rainfall extremes which wreak damage on agriculture, infrastructure and people. Tropical cyclones, such as Enawo which battered Madagascar in March, can severely impact low-lying, highly populated regions through intense rainfall combined with strong winds and storm surges. Explosive thunderstorms operating at smaller spatial scales can generate flash flooding and may lead to devastating landslides in mountainous terrain. A sustained dearth of rainfall or multiple failed seasonal rains, as implicated in drought currently impacting Somalia, Kenya and Ethiopia, are also inextricably linked with evolving weather patterns, often driven by the slower heart-beat of the oceans as they pace out the internal rhythm of El Niño Southern Oscillation and its decadal counterparts. Continue reading Changing wet and dry seasons →

What have global temperatures ever done for us?

observations, precipitation, temperature, variability

Much attention is rightly given to changes in global mean surface temperature – it is the key metric for assessing how our climate is changing and evaluating mitigation strategies. However, no-one directly experiences changes in global mean temperature – it is only through local variations that changes in climate are felt.

So, what have global temperatures ever done for us? Continue reading What have global temperatures ever done for us? →

Projected changes of precipitation and temperature extremes

extremes, precipitation, projections, temperature, uncertainty, variability

Model projections of heavy precipitation and temperature extremes include large uncertainties. However, disagreement between individual simulations primarily arises from internal variability, whereas models agree remarkably well on the forced signal.

Post based on Fischer et al., 2014, Geophys. Res. Lett.
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Wet get drier (eventually)?

GCMs, precipitation, projections, uncertainty

A prevailing paradigm of how rainfall patterns will change on a warming Earth is that the hydrological cycle strengthens causing wet regions to get wetter and dry regions to get drier.

However, this is not always the case: Hawkins, Joshi & Frame (2014) highlight one particular effect – the movement of the Inter-Tropical Convergence Zone (ITCZ) – as a key long-term driver of rainfall changes that do not follow this ‘wet get wetter’ paradigm. Continue reading Wet get drier (eventually)? →