The best way to respond to a new IPCC report is to tune out all the press coverage and look at the actual document, which is the last thing most people think to do. So over the next few weeks we are providing excerpts of the text of the new IPCC AR6 WG1 draft report on the big topics of the day, especially apocalyptic extreme weather and the like. This week: Droughts. The IPCC (Chapter 11) discusses various mechanisms that cause drought conditions, so this week we start with insufficient rainfall (“precipitation deficits”). We'll use “(---)” to mark where we skip lists of journal article references to make it easier to read. And other than spelling out some short forms, here from Sct. 126.96.36.199 is the IPCC in its own words on precipitation deficit-induced droughts.
Strong precipitation deficits have been recorded in recent decades in the Amazon (2005, 2010), southwestern China (2009-2010), southwestern North America (2011-2014), Australia (1997-2009), California (2014), the middle East (2012-2016), Chile (2010-2015), the Great Horn of Africa (2011), among others (---). Global studies generally show no significant trends in [Standardized Precipitation Index] time series (---), and in derived drought frequency and severity data (---), with very few regional exceptions (Figure 11.17 and Section 11.9).
Long-term decreases in precipitation are found in some AR6 regions in Africa (Central Africa, East-Southern Africa), and several regions in South America (North-East South America, South American Monsoon, South-West SA, South SA) (Section 11.9). Evidence of precipitation-based drying trends is also found in Western Africa (West Africa), consistent with studies based on Consecutive Dry Day trends (---) (Figure 11.17), however there is a partial recovery of the rainfall trends since the 1980s in this region (Chapter 10, 10.4.2.1). Some AR6 regions show a decrease in meteorological drought, including North Australia, Central Australia, Northern Europe and Central North America (Section 11.9). Other regions do not show substantial trends in long-term meteorological drought, or display mixed signals depending on the considered time frame and subregions, such as in Southern Australia (---) and the Mediterranean (---) (see also Section 11.9 and Atlas 8.2).