By Cassandra Garrison
MEXICO CITY, July 2(Reuters) - A long-term drought that has hit two-thirds of Mexico looks set to worsen in coming weeks, with forecasts warning of high temperatures, crop damage and water supply shortages on the horizon, including in the populous capital.
Experts are sounding the alarm that parched crops could under-produce as temperatures hit 40 degrees Celsius (104F) on Wednesday in some parts of northern Mexico, including key farming areas.
"In some states, irrigation is practically disappearing due to lack of precipitation," said Rafael Sanchez Bravo, a water expert at Chapingo Autonomous University, noting low reservoirs and reduced water transfers to farms.
Mexico's drought parallels that of the western United States and Canada, where crop yields are threatened and water rationing has been imposed.
While rains were only 3% below average across Mexico as a whole last year, the strain on water reserves was exacerbated by increased domestic demand during the COVID-19 pandemic, a U.S. government report showed last month.
Hopes to replenish Mexico's parched reservoirs now hinge on the traditional rainy season, known formally as the North American Monsoon, which is now underway.
"The next three months will be really crucial in how this drought turns out," said Andreas Prein, an atmospheric scientist for the National Center for Atmospheric Research in Boulder, Colorado.
Much of Mexico gets between 50% and 80% of its annual rainfall between July and September.
Water shortages are common in parts of Mexico, but have worsened amid heat extremes blamed on climate change, according to scientists and data from federal water commission CONAGUA.
About 70% of Mexico is impacted by drought, up from about half in December. About a fifth of the country is experiencing extreme drought compared to less than 5% each year since 2012.
Experts fear the problem will reach more of the 22 million inhabitants of Mexico City's metro area, which is quenched by a network of reservoirs. Some districts have no piped drinking water at the best of times.
"I have no doubt that in 2022 there will be a crisis," said Sanchez, who anticipates possible social unrest. "The reservoirs are completely depleted."
Sanchez is encouraging local authorities to invest in collecting rainfall for domestic use.
Villa Victoria, an important source for Mexico City, was among 77 of 210 principal reservoirs below 25% capacity at the end of June, according to CONAGUA data. Cracked lake beds can be seen at others around the city.
Images by a European Commission satellite show a visible depletion at Villa Victoria on June 15 of this year, compared to June 30 last year when it was already half empty.
This time last year, there were 56 reservoirs below 25% capacity. Two years ago, there were just 40.
The drought has prompted the government to seed clouds with silver iodide over the next three months in a trio of northern farming states - Sinaloa, Sonora and Chihuahua - in a bid to induce rain with the help of specially-equipped air force planes, according to an agriculture ministry statement.
But this year's corn production target of 28 million tonnes is still at risk.
"The scenario is pessimistic and we can't deny we're worried," said a senior agriculture ministry official, speaking on condition of anonymity.
It can be difficult for scientists to attribute any single event to climate change, but more extreme droughts point to warming global temperatures that researchers say is due to greenhouse gas emissions, said Prein.
The heat saps moisture from soil.
"That's a big deal. If you are already in a very dry region like the western part of Mexico and you increase the temperature, you lose a lot of water just by evaporation," said Prein. (Reporting by Cassandra Garrison; Additional reporting by David Alire Garcia Editing by Alistair Bell)
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