The storms that lashed Northland last week are a taste of the weather Kiwis can expect more often, says the co-author of an international study of climate change.
The State of the Climate in 2013 report, released overnight by the American Meteorological Society, shows the planet is continuing to heat up.
The report, compiled by 425 scientists from 57 countries, shows Southern Hemisphere countries particularly had a warm 2013; Australia had its warmest year in more than a century of records, while Argentina had its second-warmest.
In New Zealand, the winter of 2013 was the warmest ever and the year turned out third-warmest overall.
At two-tenths of a degree above the average of the three decades to 2010, the globally averaged sea surface temperature last year was among the 10 warmest on record, and sea levels continued to rise.
The amount of carbon dioxide in the atmosphere jumped to 400 parts per million - a rate not been seen for several million years - and the Arctic is continuing to warm at double the global rate.
In Europe, devastating floods in the spring resulted in 24 deaths and caused billions of dollars of damage.
Asia's extreme weather events included super-typhoon Haiyan, one of the strongest cyclones ever recorded.
More than 6000 people died as a result of the cyclone and two million were left homeless.
Extreme heat in January meant some locations in Australia recorded temperatures of at least 10C above average for several days.
Victoria University climate scientist Associate Professor James Renwick, one of four international scientists who presented the report, said its findings were unsurprising but sobering.
"Climate change does not mean a few extra nice days in summer - we are talking about a significant alteration in the climate," said Dr Renwick, who had overall responsibility for the report's climate summaries covering Europe, Asia and Oceania.
"The sort of temperatures we are calling warmer than average now will be considered colder than average in 50 or 60 years - that's how quickly the climate is changing."
The weather that wreaked havoc in Northland last week showed what Kiwis could expect in the future, he said.
"The region has had a number of very dry summers in recent years and has now experienced much higher than normal rainfall.
"Going from drought conditions to very heavy rain and flooding is exactly the kind of pattern we can expect from climate change."
Dr Renwick told the Herald that action was needed now if the world wanted to avoid the consequences of climate change.
He believed "a genuine cross-party commitment" was needed.
"New Zealand could so easily lead the world on this critical issue, and we could reap the economic and global political benefits.
"The current Government's approach is a massive missed opportunity, and a failure of imagination."
• During 2013, the amount of carbon dioxide in the atmosphere reached the milestone level of 400 parts per million for the first time in several million years.
• A globally averaged sea surface temperature for 2013 was among the 10 warmest on record.
• Sea levels continued to rise. In just the past 20 years, global average levels have risen by 7cm.
• In the past half century, Arctic temperatures have risen about 1.5C, and that region of the planet is warming up at roughly double the global rate.