2015 may be the warmest on record, but heat waves will only intensify unless we act now

The UN’s meteorological agency says the global average surface temperature in 2015 is likely to be the warmest on record. The Hong Kong Observatory believes this year will be the city’s warmest since records began in 1884. In India, a severe heat wave claimed the lives of more than 2,500 people in May. And, three months ago, Hong Kong experienced its hottest day on record.

The message is clear. Despite fluctuations, on a long-term scale, global temperatures are unquestionably rising. Hong Kong is beginning to feel the wrath of summer heat and the gradual blurring of the seasons.

Many scientific studies have concluded that this year’s sporadic weather pattern is not an aberration but a direct result of the sustained warming of our climate. The consequences are more than just the discomfort brought by hotter days. The extreme weather conditions experienced in many parts of the world may be linked to sustained climate change.

As a climate scientist, my current research on heat waves in East Asia (and two of my earlier studies focusing on North America and Europe) suggests that unless we act responsibly now, hot weather will prevail and intensify. Heat waves will not only become more frequent, but will last longer and be more severe. Coastal cities like Hong Kong will also be affected.

In 2012 and 2014, I collaborated with colleagues at the US Geophysical Fluid Dynamics Laboratory and the Chinese University of Hong Kong on two separate studies on extreme weather events in North America and Europe. This year, the research procedure and projections were repeated for East Asia.

These studies point to a consistent trend: as we head towards the end of this century, there are likely to be more than twice as many heat waves each year; and each is likely to last up to twice as long. These changes are equally likely in East Asia, Europe and North America.

In reaching our projections, we are already assuming that global-warming-contributing emissions will be reduced by half of the current level by 2080. Even with these efforts, the average global temperature will rise by about 2 degrees Celsius by 2100. If our energy consumption grows at current rates, the increase in emissions could easily push the temperature up by as much as 4 degrees, with even more extreme weather events.