We should have been talking a lot more about the climate

This week, the Melbourne-based Breakthrough - National Centre for Climate Restoration - published a paper by David Spratt and Ian Dunlop called Climate Dominoes.

They warn that abrupt change is happening earlier and/or faster than projected only two decades ago. For instance, the Arctic sea-ice collapse is "100 years ahead of schedule". At 1.2 degrees warming tipping points (a critical threshold when a system passes from one state to a different state, often irreversibly) have been passed for several earth systems such as the Greenland ice sheet, the world's coral systems and glaciers in west Antarctica.

The authors warn that climate models do not incorporate key processes, such as the stalling of the Gulf Stream, and thus are not reliable. The Earth's climate system is undergoing abrupt change.

They go on to say that accelerated warming may drive the Earth past "hothouse earth" conditions, even within the 1.5-2 degree window, and we are likely to exceed two degrees in the 2040s. These risks have been underestimated, they argue, not least sea-level rise which, even at current temperatures, may be five to 10 metres higher, or at current carbon dioxide concentrations, five to 25 metres higher.

Even decarbonisation may not be enough to save us. Active cooling of the Earth through geo-engineering techniques may be necessary to keep us below critical temperature thresholds. We're certainly not talking enough about climate. It's time we did.

Anyone who has travelled on Canberra's public transport system for as long as I have (since the 1950s) will know that the light rail has been a game-changer in terms of its capacity to attract patrons and provide a smooth, reliable and regular service.

Our city needs more people to use public transport in the future, and the investment in extending light rail will prove far more effective than relying on rubber-wheeled vehicles on roads.

When are our senior politicians ever going to learn English grammar - particularly the instrumental case. I just heard Labor's finance spokesman say "with Katy and I". Time and time again, I've heard Scot Morrison say something like "to Jenny and I". They're not alone - these days, whether it's "with", "to", "from" or any of these simple terms, even the most educated people are using "I" when it should be "me". It's rife among news presenters, and I recently even heard a High Court Judge get it wrong.

It really isn't hard. You wouldn't say "come along with I", so why would you say "come along with Fred and I"?

The Federal ALP states attention should be on the quality of expenditure proposals so benefits to the community can be maximised. Unfortunately, the ACT Labor government does not have such a focus.

Canberra light rail has been found by the Productivity Commission, Infrastructure Australia and other experts to be a poor use of public funds, funds which would provide greater benefits if used for other purposes including social housing, health and improved bus services, including the more rapid electrification of bus fleet.

Douglas Mackenzie wrote (Letters, May 19) that if Peter Dutton were to become Prime Minister he would emigrate to New Zealand. Please do not wait. Having read so many of his letters I am sure that he would be far happier under the muddle-headed left-wing regime of Jacinda Ardern.