The year 2018 is on course to be the fourth warmest on record, according to the World Meteorological Organization.
Extreme weather has affected all continents, while the melting of sea ice and glaciers and sea level rises continue.
With greenhouse gas concentrations at record levels, Mr Taalas said that we may see temperature increases of between three and five degrees Celcius by the end of the century if greater action is not taken now.
The organization's report also highlighted events during the current year, such as floods in the Indian state of Kerala and Japan, and heat waves in much of Europe, including the United Kingdom, which caused forest fires in places like Scandinavia.
"It is worth repeating once again that we are the first generation to fully understand climate change and the last generation to be able to do something about it", Professor Taalas said.
Adding weight to the WMO's assessment is another climate study released on Thursday by The Lancet Countdown on Health and Climate Change.
More than 150 million vulnerable people worldwide were affected by potentially risky heatwaves previous year, it said, while a total of 153 billion work hours were lost owing to unusually hot weather. It makes a difference to the speed of glacier melt and water supplies, and the future of low-lying islands and coastal communities.
The meeting is to adopt the implementation guidelines of the Paris Agreement on Climate Change, which aims to hold the global average temperature increase to as close as possible to 1.5 degrees Celsius. Every extra bit matters, ' said Ms Manaenkova.
Summer temperatures could be up to 5.4°C hotter and summer rainfall could decrease by up to 47 per cent by 2070, the report states. London could become increasingly vulnerable to storms and flooding due to sea-level rises, with the water level in the capital likely to rise by 1.15 metres by the end of the century.
"If we exploit all known fossil fuel resources, the temperature rise will be considerably higher", he warned. The year started with a weak La Niña event but by October there were signs of a return to El Niño conditions, which can raise global temperatures further.
The number of tropical cyclones was above average in all four Northern Hemisphere basins, with 70 reported by 20 November, compared to the long-term average of 53, leading to many casualties.
'The record-high heatwaves, record-low Arctic sea ice, above average tropical cyclones and deadly wildfires are an alarm bell impossible to ignore.
Jens Mattias Clausen, Greenpeace's head of delegation at COP24, said: "The evidence, if we needed any more, continues to stack up". It's no longer our future that is in peril; our today is at risk.
A cerrar con broche de oro, Tri en Mundial Sub17
Finalmente, las dirigidas por Mónica Vergara supieron exprimir el reloj hasta dictaminar su primer pase a la final de un mundial femenil en la historia.