Climatologists, drawing on scientific evidence, attribute present-day climate change primarily to greenhouse-gas emissions from human activities, especially industrial activity. The original article discusses major emitting economies and the Paris climate agreement, adopted at the UN climate conference in Paris in December 2015, as part of international efforts to limit the accumulation of greenhouse gases in the atmosphere.
The consequences of global warming cannot be covered in a few lines. The source emphasizes that the risks extend across ecosystems and human societies and that greenhouse gases already accumulated in the atmosphere can continue to influence climate for decades to centuries. It also notes the unequal distribution of climate impacts: some countries that have contributed relatively little to greenhouse-gas emissions may nevertheless experience severe consequences.
What are warming stripes?
One particularly intuitive way of visualizing warming is through warming stripes. The stripes reproduced in the original article show changes in average air temperature for different Iranian cities over approximately 170 years. Each broad strip consists of many thin vertical lines, with each line representing the temperature anomaly for one year. The sequence begins with the earliest data around 1850 and runs through 2020 from left to right.
The colour of each yearly stripe is determined by the difference between that year's mean temperature and the mean temperature during a reference period. For the visualization described here, the reference period is 1951–1980.
A red stripe means that the year's mean temperature was warmer than the reference-period average, while blue indicates a cooler year. The darker the colour, the larger the departure: deep red represents a substantially warmer year and deep blue a substantially cooler one. Pale red or blue represents a smaller difference, while a nearly white stripe indicates a temperature close to the reference average.
Viewed as a whole, the Iranian warming stripes contain alternating warm and cool years, but their long-term pattern changes markedly. The older portion—roughly 160 to 170 years ago—contains substantially more cool-coloured years. Moving toward the present, the stripes gradually shift from blue toward red, with particularly strong red tones appearing during roughly the final two to three decades represented in the graphic.
The visual message of the chart is therefore the long-term rise in average temperature: despite year-to-year variability, recent decades in the represented Iranian cities are markedly warmer relative to the historical reference period.
The dates, country references, and Paris Agreement figures above reproduce the framing and information in the original 2020 article rather than updating them to present-day values.