Using observational rainfall datasets, we identify a positive correlation between precipitation over Central Equatorial Africa (CEA) and the Indian Ocean Dipole (IOD) during September‐December (SOND) for the period 1981–2019. Rainfall amount significantly increases during positive IOD events. The enhancement in precipitation is primarily attributed to increased rainfall frequency and reaches the maximum in October. IOD impacts rainfall via modifying the Walker circulation over the tropical Indian Ocean and moisture in the middle troposphere over CEA. The Madden‐Julian Oscillation (MJO) activity covaries with IOD to modulate the African Easterly Jet, which is critical to convection development over CEA. SOND rainfall has increased for the last two decades, which is concurrent with increases in both the IOD index and the correlation between IOD and rainfall. The IOD‐congruent rainfall changes potentially account for much of rainfall trends in southern and eastern CEA.

Mapping and monitoring regional fire activity are essential to understand their responses to human activities and climate change. Here we use multiple sources of observations, reanalysis data, and model simulations to examine the responses of fire activity to climate change over northeastern China in the past two decades. We detected significant positive burned area (BA) trends in this region since 2003 during spring and much stronger interannual variations in BA in the last decade. We then separated the study region into cropland and natural vegetation and found that the increasing BA trends come mainly from agricultural burning. Our results also show that temperature is the dominant driver for BA variations in natural vegetation, whereas agricultural burning is influenced by precipitation, although human activities largely contribute to BA variations due to farming practices and land use and management. Our results further suggest that tropical North Atlantic (TNA) sea surface temperatures (SST) variability regulates the fire weather conditions (temperature and precipitation) in northeastern China through the Rossby wave train from the tropical Atlantic to the Eurasian continent. The cooling of TNA SST since 2010 could induce an anomalous anticyclonic circulation around Northeast Asia, leading to sinking motion and divergence in the region and resulting in reduced precipitation and warm temperatures. Thus, the co-occurrence of warm and dry anomalies has led to more frequent burning since the 2010s. Our study not only detects recent BA variations in northeastern China but also provides further evidence for the remote impact of TNA variability on recent BA and climate variations over the region.

Food security depends on water availability; understanding the sources of atmospheric moisture for different crop producing regions is thus critical. Here, using Earth observations and physical and statistical models over the period 2003-2019, we explore the extent to which atmospheric moisture for the world’s major crops originates from oceans versus land. By integrating precipitation isotope observations and two satellite-derived atmospheric water isotope products, we find that the percentage of crop water originating from land varies from ~25% to 75% over the year, with strong variation over crop growing seasons and crop phenological stages. Although patterns vary by region, ocean-originating moisture tends to provide most precipitation during the vegetative and reproductive stages of the main crop growing season. Linking source and water supply information shows that crop water stress becomes more likely later during the reproductive period, due to continuous and increasing soil moisture depletion, and this phenomenon is much stronger for croplands dependent on land-originating moisture. This stress is highly associated with crop productivity as measured by greenness (NIRv): we find that croplands with ≥40% of moisture derived from land are more susceptible to water stress than those with <40%. Importantly, when disaggregated by crop type, we find that over 40% of the world’s maize and over 50% of the world’s wheat receive more than 40% of their moisture from land during the critical reproductive stage. For these areas, simple hydrological metrics -- integrated rainwater supply and root-zone soil moisture -- explain up to 60% of inter-annual variability in crop greenness. These results thus provide valuable insights for understanding dimensions of the vulnerability of global crop production and potential adaptation responses, including protection of local land moisture sources, selection of suitable crops, and design of smart irrigation strategies at sub-seasonal scales.