As scores of people are dying from scorching temperatures across the south of the United States, Vice-President Al Gore has accused Republican opponents of ignoring global warming through budget cuts.
US government agencies have produced figures showing that last June, on a global basis, was the hottest in more than a century of keeping climate records. Each month so far in 1988 has set a new record on a global average basis.
In the US, May and June have been disastrous for many states as drought and temperatures in the 100s fahrenheit have destroyed crops and wiped out forests. About 50 people are estimated to have died because of the heat, 23 of them in Texas and 20 in Louisiana. Florida and Arizona have also been badly hit.
"The evidence of global warming keeps piling up, month after month, week after week," Mr Gore said at the White House. "How long is it going to take before these people in Congress get the message? People are sweltering out there."
The Republican-controlled Congress opposes measures by the administration to implement the global warming treaty signed in Kyoto, Japan, last year. In a first step the White House has proposed $6.3 billion (£4.5 billion) in tax cuts and research to encourage investment in energy-efficiency but Republicans have eliminated this spending.
The Republican bill would bar any measures to implement Kyoto until it is ratified by the Senate.
"It is so incredibly unusual to have six months in a row and every one of those months sets an all-time new record for being the highest month ever," Mr Gore said. "You can see quite clearly the long-term warming trend."
The latest data has been produced by the National Oceanic and Atmospheric Administration, which describes the findings for the first half of 1998 as "remarkable and sobering". This, along with the fact that 1997 was the warmest year on record, provided "compelling evidence" that global temperatures are gradually increasing, the senior climate researcher Mr Tom Karl said.
But some climate experts are doubtful about using short-term temperature data to predict long-term global warming. Mr John Christy, a climatologist at the University of Alabama, said that "you see a situation where the surface of the earth is warming and the troposphere [up to 10 miles high] is not. In an enhanced greenhouse system it's supposed to be the opposite."
But Mr Karl says that satellite data, depending on how it is interpreted, shows some warming in the upper atmosphere.