Land cover and land management changes (LCLMCs) play an important role in achieving low-end warming scenarios through land-based mitigation. However, their effects on moisture fluxes and recycling remain uncertain, although they have important implications for the future viability of such strategies. Here, we analyse the impact of idealised LCLMC scenarios on atmospheric moisture transport in three different Earth system model (ESMs): the Community Earth System Model (CESM), the Max Planck Institute Earth System Model (MPI-ESM), and the European Consortium Earth System Model (EC-EARTH).

The LCLMC scenarios comprise of a full cropland world, a fully afforested world, and a cropland world with unlimited irrigation expansion. The effects of these LCLMC in the different ESMs are analysed for precipitation, evaporation, and vertically integrated moisture flux convergence to understand the LCLMC-induced changes in the atmospheric moisture cycle. Then, a moisture tracking algorithm is applied to assess the effects of LCLMC on moisture recycling at the local (grid cell level) and the global scale (continental moisture recycling). By applying a moisture tracking algorithm on fully coupled ESM simulations we are able to quantify the complete effects of LCLMC on moisture recycling (including circulation changes), which are generally not considered in moisture recycling studies.

Our results indicate that cropland expansion is generally causing a drying and reduced local moisture recycling, while afforestation and irrigation expansion generally cause wetting and increased local moisture recycling. However, the strength of this effect varies across ESMs and shows a large dependency on the dominant driver. Some ESMs show a dominance of large-scale atmospheric circulation changes while other ESMs show a dominance of local to regional changes in the atmospheric water cycle only within the vicinity of the LCLMC.

Overall, these result corroborate that LCLMC can induce substantial effects on the atmospheric water cycle and moisture recycling, both through local effects and changes in atmospheric circulation. However, more research is needed to constrain the uncertainty of these effects within ESMs to better inform future land-based mitigation strategies

This study was part of our project on land management strategies to mitigate and adapt to climate change

Climate impacts and risks

Publications

Humid heat exceeds human tolerance limits and causes mass mortality

With critical physiological limits to human heat tolerance drawing ever closer, this Comment highlights the urgent need to limit further climate warming and emphasises the adaptation challenge ahead.

Spatially resolved emulated annual temperature projections for overshoot pathways

This study presents a new dataset of annual temperature projections for different overshoot pathways (when the 1.5 °C of global warming limit is exceeded). The data offers a unique opportunity to study local and regional climate change impacts of a range of overshoot scenarios, including when temperature thresholds might be exceeded, and by how much.

Geological Net Zero and the need for disaggregated accounting for carbon sinks

This study in Nature show that definitions of net zero now in widespread use will not actually stop global warming. The paper demonstrates that relying on natural carbon sinks, such as in forests or oceans, to 'offset' ongoing fossil fuel emissions will lead to continued warming.

The role of northern forests in limiting warming to 1.5°C

Northern forests are critical in the race to net zero CO₂ by mid-century. Protecting and restoring these forests, alongside steep and rapid reductions in fossil fuel emissions, is essential both to mitigating emissions and to supporting forest ecosystem services and biodiversity.

Rapid urbanisation and climate change key drivers of dramatic flood impacts in Nepal

New study finds the devastating floods in Nepal late September were exacerbated by rapid urbanisation and climate change. The analysis found the relentless rain, which fell on saturated ground in the late monsoon, was made at least 10% heavier and 70% more likely by climate change.

Seasonal forecast of two-metre temperature and precipitation in Tanzania: A hybrid cluster and point-by-point machine learning approach

Seasonal forecasting of atmospheric parameters is important in various fields including agriculture. This study tests how machine learning can complement dynamic models using Tanzanian seasonal forecasts and finds this process uses far less computational power.

Overconfidence in climate overshoot

Even if it is possible to reverse the rise of global temperatures after a temporary overshoot of 1.5°C, some climate damages triggered at peak warming, including rising sea levels, will be irreversible, according to a new study published today in Nature.

Solar geoengineering: a note to inform discussions on physical climate impacts, risks and governance issues

With international efforts on climate action still not on track to limit warming to 1.5°C, technological fixes that aim to intentionally alter the Earth’s climate, such as solar geoengineering, might seem like appealing options for tackling global warming. But they come with questions in terms of feasibility, impacts and risks, governance and geopolitics, and who may or may not benefit.

How can event attribution science underpin financial decisions on Loss and Damage?

With climate extremes hitting nations across the globe, disproportionately burdening vulnerable developing countries, funding for loss and damage is an acute need. Attribution science can provide useful information for decision makers.

Achieving net zero greenhouse gas emissions critical to limit climate tipping risks

Current climate policies are putting Earth on a path to a high risk of triggering climatic tipping points – even if temperatures return to below 1.5°C of global warming after a period of overshoot. A new study finds that the risk of crossing these thresholds increases with every additional 0.1 °C of overshoot above 1.5 °C and strongly accelerates above 2.0 °C. These risks can be minimised if stringent emissions reductions are taken in the next decade, and net zero greenhouse gas emissions are met and maintained.

Evaluating the near and long-term role of carbon dioxide removal in meeting global climate objectives

For 1.5°C pathways with limited overshoot, most of the mitigation between now and 2030 should come from emissions reductions (70%), with reductions from cutting non-CO2 emissions (20%) and land-based carbon dioxide removals such as afforestation and preventing deforestation (10%) making up the remainder.

Increasing April-May rainfall, El Niño and high vulnerability behind deadly flooding in Afghanistan, Pakistan and Iran

This April and May, large regions of central Asia were hit by a series of storms resulting in heavy downpours and flash flooding. Researchers assessed what extent human-induced climate change altered the likelihood and intensity of the weather conditions that caused the floods.

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Decarbonisation targets and 1.5℃ pathways

Comment

Effects of idealised land cover and land management changes on the atmospheric water cycle