Shell script to print the current weekly mean value Mauna Loa CO2 value

climate.sh

#!/bin/bash                                                                                                                                                                       

# Prints the current weekly mean value Mauna Loa CO2 value, and                                                                                                                   
# compares it to the value from 365 days ago.                                                                                                                                     

# Thanks to Pieter Tans <[email protected]> for data guidance.                                                                                                                 

url="ftp://aftp.cmdl.noaa.gov/products/trends/co2/co2_weekly_mlo.txt"

line=`curl -s $url | tail -n 1`
curr=`echo "$line" | cut -c 30-35`
year=`echo "$line" | cut -c 50-55`
diff=`echo "$curr - $year" | bc`

echo "Current Mauna Loa CO2: $curr ppm"
echo "365 days ago: $year ppm"

if [ "$diff" == "0" ] ; then
    echo "→ no change since last year"
elif [[ $diff =~ ^- ]] ; then
    echo "→ ${diff#-} ppm lower than last year"
else
    echo "→ $diff ppm higher than last year"
fi

see also: https://twitter.com/dphiffer/status/1115348317515460610