Highlights:

It is no longer news that climate changes are, quite literally, reflected through water. The combined challenges of flood and drought already impact a fifth of the world’s population, disproportionately affecting vulnerable communities and ecosystems. These impacts are projected to rise drastically absent affordable adaptation solutions. Nature-based Solutions (NbS), deployed at scale and in the right places, have broad applicability to the mitigation of flood and drought and to helping communities adapt to climate change. Nevertheless, the global extent of their applicability remains misunderstood. This report offers guidance to disaster risk planners and adaptation funders on where and how to effectively harness nature to adapt to both a wetter and drier future.

• Water-related hazards like flood and drought are among the most damaging natural disasters on Earth. More than 1.8 billion people (roughly 20% of the global population) are estimated to have experienced large flood events over the last 20 years, with flood damages during that time reaching US$650 billion— equivalent to the GDP of Sweden. On the other hand, drought was responsible for 650,000 deaths, or nearly one-third of disaster-related deaths between 1970–2019, and drove an estimated US$124 billion in losses between 1998–2017.

• Climate change is increasing the frequency, intensity and distribution of floods and droughts for many regions, with disproportionate impacts to some countries.

• Nature-based Solutions can play a major role in mitigating the water-related impacts of climate change, but the synergies, trade-offs, and potential magnitude of the impacts of NbS on future flood and drought risk remain poorly understood.

• This report identifies synergies and trade-offs of different Nature-based Solutions for flood and drought.

• This report describes which Nature-based Solutions may be particularly good at reducing flood and drought risk in diverse contexts.

• This report finds that there is broad global applicability for Nature-based Solutions for flood and drought, notably in areas expected to face the greatest increased risks of climate-driven flood and drought.

• Disaster risk planners and adaptation funders interested in exploring NbS for drought and flood can learn from projects that have already been implemented.

• To address the impacts of climate change, adoption of Nature-based Solutions must be considered both as a complement to, and possible substitute for, existing management and infrastructure investments. Despite the critical need for increased investment in climate adaptation, less than 10% of total climate funding in recent years has gone toward adaptation. Current spending on adaptation needs to increase by a factor of three to seven by 2030 to meet the needs of communities in the face of expected climate change impacts.