Climate change is among this century’s greatest challenges to the wellbeing of people across the world, including in the US and Cambodia. The impact of climate change is particularly relevant this week, as we mark World Water Day and the International Day of Forests.

Cambodia is home to some of Southeast Asia’s most significant intact tracts of forest and to the largest inland body of freshwater in the region, formed by the mighty Mekong River and the singularly unique Tonle Sap. As US ambassador, I have travelled to every province in the Kingdom and have had the privilege to visit these natural wonders, so important for the livelihoods and food security of the Cambodian people.

I have marvelled at the country’s beauty and biodiversity, from the amazing creatures of the Phnom Tnout Phnom Pok Wildlife Sanctuary and dazzling offshore islands ­– to the old growth forests of the Cardamom Mountains and the breathtaking ocean vistas at Kep National Park.

I have also seen first-hand the significant pressures, including from climate change, on these protected but vulnerable natural resources.

The Kingdom’s precious biodiversity is in danger of literally disappearing, threatening Cambodia’s sustainable development and prosperity.

We can and must do more together to prevent this from happening.

I’m particularly proud that the US puts climate change front and centre in our foreign policy and diplomacy.

Among President Joe Biden’s first actions in office was to rejoin the Paris Climate Agreement and to announce that the US will host a Climate Summit next month on Earth Day to “raise the ambition of all nations, including our own, to rapidly lower global carbon emissions”.

At the same time, the US has pledged to continue assisting partners around the world, including here in the Mekong region, to mitigate the effects of climate change.

Climate change isn’t the only challenge, however, that Cambodia and other Mekong countries face in protecting the region’s natural resources. Upstream and opaque hydropower projects – completed with little regard for environmental impact – sand mining, deforestation, wetland conversion,

corruption and pollution are immediate, man-made challenges that have resulted in a dramatic drop in water levels in the Mekong River and Tonle Sap, disrupting fishing and threatening Cambodia’s food security.

Shockingly, over just the last couple of years, water levels in both rivers are down by two-thirds and fish catches have dropped by over 70 per cent.

The US has a long and valued partnership with the region to address these issues. The Mekong-US Partnership (MUSP), launched last year, builds on the successful framework of the Lower Mekong Initiative that was established to tackle these various threats. As a senior diplomat in Washington and across Southeast Asia, I was proudly part of our effort a decade ago to establish this framework, through which the US provided $3.5 billion in assistance to the five Mekong partner countries, including Cambodia.

The new MUSP supports data-sharing initiatives like the Mekong Dam Monitor, which is bringing transparency to Mekong basin-wide dam operations. The monitor is an open-source data initiative – freely available for public use – that employs satellite imagery with remote sensing technology to provide near-real time reporting on water levels and dam operations.

This gives downstream countries like Cambodia essential information for addressing water-related challenges.

In collaboration with all five Mekong countries, the MUSP also promotes environmental protection, including sustainable water and natural resources management. In fact, just last week, the MUSP gathered regional representatives from partner governments, the private sector, and non-governmental organisations to explore solutions to common challenges in energy, infrastructure, non-traditional security and water governance.

World Water Day, the International Day of Forests, and Earth Day are all important markers on the calendar.

These milestones are only significant, however, if they motivate us to action to address our shared climate and environmental challenges.

The MUSP and other US-supported programmes – including through ASEAN – demonstrate our commitment to Cambodia and Mekong region countries to do just that. We must do so for the health of our peoples, our economies, our security, and our shared planet.

Patrick Murphy is US ambassador to Cambodia