Simplistic Overview of Climate Target 1.5°C


If like me you have read about global warming and the efforts to try to reduce this you may have heard about a target of 1.5°C which we can’t let the earths temperature rise above. But what exactly does that mean? I had no idea so thought would do a little investigation to find out.

The Paris Agreement

Once a year people may notice all the world leaders or their delegates meet to discuss climate and global warming issues, it usually makes the news and papers and is known as Conference of the Parties or COP for short. The Paris Agreement is a legally binding international treaty on Climate Change, this is agreed up during the United Nations (UN) Climate Conference COP. This treaties goal is to stop the global average temperature rising above 2° C above pre-industrial levels, ideally limiting it a rise of 1.5° C.

My next questions were:

  • Why was this target chosen?
  • What is the baseline temperature?
  • How hot is 1.5° C?
  • When was the pre-industial age?

Temperature Scale

Celsius is the scale we are use to dealing with day to day, Water boils at 100° Celsius and freezes at 0° Celsius. So a 1.5° C raise does not seem that high based on our day to day experience. If the Temperature was 20°C yesterday and 21.5°C today we would not really notice that much.

So why was 1.5°C such an important target?

The decision to include a 1.5°C target in the Paris Agreement was based on scientific research that shows the serious and potentially irreversible impacts of global warming beyond this threshold, particularly for vulnerable communities and ecosystems.

My history is a little rusty when was the Pre-Industrial Ages?

This refers to a time before machines and tools were common place, Wikipedia has this to be between 1750 to 1850. “The industrial revolution where machines started to be used can also be considered to have occurred from around 1760 to about 1820–1840”. Other references such as BBC state 1720 to 1800 may be a more accurate measure.

How is Global Temperature Measured?

Measuring Global temperature is a 5 step process which consists of dividing the planet up into 1000s of pieces and measuring temperature averages for each area as below:

1. Measure temperature above land and the ocean in 1000s of places around the world

2. Subtract the temperature you measure at each location from the usual temperature on that day, this difference in temperature is called the ‘Anomaly’

What is ‘normal’ temperature for a location and time, this typically the long-term average over a 30-year period.

A ‘positive’ anomaly means the temperature is warmer than the long-term average, a ‘negative’ anomaly means it’s cooler.

3. Repeat steps 1 and 2 for each day of the year

4. Divide the planet into a grid of 2,592 squares.  Calculate the average temperature anomaly for each square.  At the end of the year you will have 946,080 temperature anomalies resulting from 2,592 locations in the grid multiplied by 365 daily temperatures.  

5. Take the average of all temperature anomalies from all over the world.  Compare this with other years.

As we can see it takes quite some effort and record keeping to derive a global temperature. This practice really became reliable from 1850 onwards. But Scientists mark the start of modern global record-keeping as 1880. That’s because earlier available climate data doesn’t cover enough of the planet to get an accurate reading, according to NASA.

What was the Global Average Temperature in 1880?

As we can see global temperature record keeping became more reliable from 1850 but its not until 1880 that scientists accept the data is accurate enough and covers enough of the earth to be reliable. So 1880 could be our potential baseline and is not too far off of the pre industrial era which some say ended in 1850.

The global average temperature of the Earth in 1880 was estimated to be approximately 13.8°C according to NASA’s Goddard Institute for Space Studies (GISS) temperature record.

What is the change in Global Temperature since 1880 to 2022?

Now the data for 2023 is not yet ready and takes months to aggregate and analyse, but the temperature global temperature has risen 0.89°C since 1880 so we getting closer to that 1.5°C target.

Download data from Nasa:

What happens if global temperature rises above 2°C?

Scientists believe a rise in global temperature over 2°C would have a major impact on the earth including:

  • Raising Sea level
  • More Frequent and More disruptive Storms
  • More Frequent and More disruptive Wild Fires
  • Extinction of various Plants and Animals
  • Human Life expectancy negatively effected from heat, pollution and disease
  • Negatively Impacting Agriculture and Food Supply

So how long do we have based on current trends until targets are breached?

According to Mercator Research Institute on Global Commons and Climate Change (MCC) who maintain a real time dooms day clock, we have as of today 27th February 2023:

  • 6 Years, 4 Months and 26 days until we reach a 1.5°C rise
  • 24 Years, 2 Months and 3 days until we reach a 2°C rise

Could the Scientists be wrong?

The way I look at it is the people predicting the impact are well educated, trained and experts in their field, they are basing their analysis on scientific research and facts. Of course they could be wrong, but its a greater risk to human kind actually all life on earth not just human to assume they are wrong when we can have a positive impact now if they are right. Time is running out we have just 6 years to get this sorted and people need to take notice now.



My name is Paul Sammy and I am just starting to learn about the field of Sustainability, in particular the environmental impact of IT on the planet. I am by no means an expert in the field of Sustainability but just at the start of my journey. Some may say I know just a little bit more about the field of IT.