The global total of carbon emissions will continue to grow, although more slowly than over the past two decades.
However the UN report says the plans are a major step forward and the 2C goal is still "within reach".
The UN believes that these national climate plans, called Intended Nationally Determined Contributions (INDCs) will form the cornerstone of a binding, global treaty on climate change that will be agreed at a conference in Paris in December.
According to the UN, the submissions now cover around 86% of global emissions: about four times the amount covered by the Kyoto Protocol, the world`s first carbon cutting treaty.
Their assessment is decidedly upbeat about the plans, despite acknowledging that taken together they point to rises in global temperatures of 2.7C above the pre-industrial level.
Scientists have determined that if temperature rises exceed 2C, this will lead to significant and dangerous climate impacts, which will especially hit the world`s poor.
UN climate chief, Christiana Figueres, said the plans were an excellent first step: "The INDCs have the capability of limiting the forecast temperature rise to around 2.7C by 2100, by no means enough but a lot lower than the estimated four, five, or more degrees of warming projected by many prior to the INDCs."
Observers say the 2.7C figure is a substantial improvement on 3.1C, which was the estimate when the plans were assessed last December.
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