Official figures have recorded nearly 73,000 forest fires in Brazil over the first eight months of the year – the highest number for any year since 2013. The majority of the fires were in the Amazon.
Environmental experts say the fires have accompanied a rapid rate of deforestation in the Amazon region. According to data from the National Institute for Space Research (INPE), the process of deforestation quadrupled this July in comparison to the same month in 2018.
Varadkar's warning came as other world leaders voiced concerns over the fires.
French President Emmanuel Macron labelled it "an international crisis" and called on the G7 to address the matter at their weekend summit, while UN chief Antonio Guterres said he was "deeply concerned."
"Our house is on fire. Literally. The Amazon, the lung of our planet which produces 20 percent of our oxygen is burning," Macron said on Twitter.
In Ireland Varadkar is already facing pressure over the Mercosur deal from the agriculture industry, particularly beef farmers.