Colombia is one of the rainiest countries on Earth, with annual mean precipitation of 2830 mm. There is considerable spatial rainfall variability across the territory between the Caribbean (∼300 mm/year) and the Pacific region (~5010 mm/year), reaching up to 12,200 mm/year in some places over the Pacific Coast [1]. Furthermore, Colombia is characterized by a complex geography and orography, with three branches of the Andean Mountain range, which, combined with its proximity to the Pacific and Atlantic oceans and the Amazon basin, generates intense land-atmosphere interactions. The dynamic interactions between topography, climate patterns, and socioeconomic factors present a set of circumstances highly predisposed to destructive hydrological hazard events.

Floods, droughts, and heatwaves strongly impact socioeconomic systems and health in Colombia. According to the World Bank, "Colombia ranks 10^th globally in terms of economic risk posed by three or more hazards. The country has the highest recurrence of extreme events in South America, with 84% of the population and 86% of its assets in areas exposed to two or more hazards" [2]. According to World Bank Group projections, by 2050, climate change in Colombia will impact 14% of the GDP corresponding to agriculture, and without adaptation, 80% of the country’s crops could be affected in more than 60% of their current areas of cultivation, especially high value perennial and export crops. They showed how the impacts of climate change on temperature and precipitation in Colombia could cause a 17–31% increase in malaria cases and a 63% increase in dengue fever cases by the end of the century [2]. In recent decades, only as a result of extreme anthropogenic heat, Colombia is calculated to have lost 4.9% of its GDP per capita [3]. If no adaptation occurs, by the end of the century, excess mortality due to future heatwaves could increase by a factor of 5 to 20, depending on climate and population scenarios, hitting a world record in Colombia [4]. This would be attributed to the overcoming of thresholds of the thermoregulatory capacity of the human body, hindered by the concomitant increase in humidity and temperature, particularly in low-elevation tropical cities. All these impacts are particularly worrisome given that, under a business-as-usual scenario, a significant increase in temperature (e.g., warm days, heatwaves) and precipitation (e.g., very wet days, rainfall intensity) extremes over the mid-twenty-first century is likely to occur in Colombia [5].

Unfortunately, several key structural problems in Colombia hinder a correct understanding and response to the current hydroclimatic dynamics. For decades, science, meteorological maintenance, and studies have been critically underfunded. The R&D expenditure in terms of percentage of national GDP fell to the alarming level of 0.29% in 2020, the lowest of the OECD countries, nine times less than the OECD average [6]. The budget approved for the Institute of Hydrology, Meteorology, and Environmental Studies (IDEAM) in 2023, adjusted for inflation, is less than what was approved in 2022. This threatens information flows in terms quantity, quality and timeliness, hampering responses to hydroclimatological hazards over the country [7]. Moreover, Colombia is decreasing weather station maintenance [8], which prevents accurate monitoring of hydrometeorological risks; therefore, accurate early warnings cannot be given to avoid loss of life or economic impacts. Meanwhile, there are only 80 meteorologists in the country, when the number required is in the region 500 [9]. The difficulties that the IDEAM has been experiencing in terms of limited specialized human resources and resources for the maintenance of the national system of hydrological and meteorological observations and measurements are of deep concern [7]. The technical and professional staff in the areas of meteorology and hydrology has been drastically reduced, which limits the capacity to obtain, validate, process, analyze and disseminate information on time. With limited funding and staff, many low-budget weather monitoring stations may only measure a limited number of weather variables, such as rainfall, making it difficult to predict weather conditions accurately. Finally, Colombia’s official climate projections still have inconsistencies and methodological shortcomings that critically inhibit evidence-based adaptation in the territories [10]. Consequently, the Fourth National Communication on Climate Change led by the IDEAM with the help of climatologists [10] needs urgent funding to improve and present the best state-of-the-art Colombian climate knowledge to people.

Furthermore, Colombia is the fifth largest emitter of greenhouse gases (GHG) in Latin America and the 40^th in the world, with an increase of 15% in the last 20 years [11]. This picture conceals large national inequities: while more than 50% of the Colombian population already meets very likely the +1.5°C global temperature increase target, the top 10% richest exceeds the corresponding carbon footprint by a factor of seven [12]. Although an ambitious climate mitigation target is set in 2020 (reducing by 51% greenhouses gases emissions by 2030), many climate specialists agree on its "insufficient" implementation [13]. Thus, national climate change policies should target big emitters more, particularly to avoid the worst consequences for Colombia. Significant national investment in climate mitigation, adaptation, and research will limit major losses for society in all sectors caused by hydroclimatological disasters.

Nevertheless, Colombian society is very aware and concerned about the climate change problem: 98% of Colombians surveyed consider that climate change is happening, and 87.5% believe that their municipality/city will not be ready to face its intensification in the coming years [14]. Disseminating and operationalizing knowledge from specialized agencies in charge of the environment, with horizontality and mutually fruitful dialogue between society, producers, and scientists, has concrete and positive impacts on climate change resilience. Generalization and incentivization of local nature-based solutions and sustainable lifestyles need structural coordinated national plans of investments by the national government. Education on climate change is fundamental to meeting climate goals, particularly Colombia’s.

Water studies should be brought to the center of the political agenda, to plan and implement current and future adaptation strategies for reducing hydroclimatic risks with all relevant actors (society, academy, companies, and government). Colombia occupies a particularly unique place on the world map concerning water and biodiversity, but many sectors in Colombia still lack key hydroclimate research insights to better adapt to future shocks: hydroelectricity, water provision (e.g. through the páramos), crops, or flood regulation, among others. Moreover, in the case of Colombia, a complex interplay between the dynamics of climate change and deforestation can profoundly perturb the hydrological cycle variability [15]. Therefore, the national government needs increased investment in science, technology, and innovation in subjects related to hydroclimatology topics (causes, impacts, and solutions).

There are many opportunities to improve the situation, and we call for a cross-sectoral prioritization of hydroclimatological research and monitoring in Colombia to strengthen societal resilience to climate change.