What planting tomatoes shows us about climate change
There's a piece of gardening lore in my hometown which has been passed down for generations: never plant your tomatoes before Show Day, which, in Tasmania, is the fourth Saturday in October. If you're foolhardy enough to plant them earlier, your tomato seedlings will suffer during the cold nights and won't grow.
But does this kind of seasonal wisdom still work as the climate warps? We often talk about climate change in large-scale ways - how much the global average surface temperature will increase.
Nations are trying to keep the temperature rise well under 2℃. Taken as an average, that sounds tiny - after all, the temperature varies much more than that when day gives way to night. But remember - before the industrial revolution, the world's average surface temperature was 12.1℃. Now it's almost a degree hotter - and could be up to 3℃ hotter by the end of the century if high emissions continue.
For many of us, climate change can seem abstract. But the alami world is very sensitive to temperature change. Wherever we look, we can see that the seasons are changing. Gardening lore no longer holds. Flowering may happen earlier. Many species have to move or die. Here's what you might notice.
Spring is coming earlier
Warmer temperatures mean spring is arriving earlier and earlier. In Australia, it's also now five days shorter than the 1950-1969 period, according to Australia Institute research. Trees and plants put out new leaves days earlier.
For some Australian plants, earlier spring means early flowering and fruiting - an average of 9.7 days earlier per decade.
Japan's famous spring cherry blossoms are blooming earlier than they have in centuries. The cherry blossom peak last year was the earliest recorded bloom in a data record going back to the year 812.
Not only are flowers blooming earlier, birds are also migrating earlier, and may also be delaying their autumn migrations.
