The sign of Judgement Day, the smoke, can be because of the hunger.

Narrated Masruq:
We were with `Abdullah and he said, "When the Prophet (ﷺ) saw the refusal of the people to accept Islam he said, "O Allah! Send (famine) years on them for (seven years) like the seven years (of famine during the time) of (Prophet) Joseph." So famine overtook them for one year and destroyed every kind of life to such an extent that the people started eating hides, carcasses and rotten dead animals. Whenever one of them looked towards the sky, he would (imagine himself to) see smoke because of hunger. So Abu Sufyan went to the Prophet (ﷺ) and said, "O Muhammad! You order people to obey Allah and to keep good relations with kith and kin. No doubt the people of your tribe are dying, so please pray to Allah for them." So Allah revealed: "Then watch you For the day that The sky will bring forth a kind Of smoke Plainly visible ... Verily! You will return (to disbelief) On the day when We shall seize You with a mighty grasp. (44.10-16) Ibn Mas`ud added, "Al-Batsha (i.e. grasp) happened in the battle of Badr and no doubt smoke, Al-Batsha, Al-Lizam, and the verse of Surat Ar-Rum have all passed .
حَدَّثَنَا عُثْمَانُ بْنُ أَبِي شَيْبَةَ، قَالَ حَدَّثَنَا جَرِيرٌ، عَنْ مَنْصُورٍ، عَنْ أَبِي الضُّحَى، عَنْ مَسْرُوقٍ، قَالَ كُنَّا عِنْدَ عَبْدِ اللَّهِ فَقَالَ إِنَّ النَّبِيَّ صلى الله عليه وسلم لَمَّا رَأَى مِنَ النَّاسِ إِدْبَارًا قَالَ ‏"‏ اللَّهُمَّ سَبْعٌ كَسَبْعِ يُوسُفَ ‏"‏‏.‏ فَأَخَذَتْهُمْ سَنَةٌ حَصَّتْ كُلَّ شَىْءٍ حَتَّى أَكَلُوا الْجُلُودَ وَالْمَيْتَةَ وَالْجِيَفَ، وَيَنْظُرَ أَحَدُهُمْ إِلَى السَّمَاءِ فَيَرَى الدُّخَانَ مِنَ الْجُوعِ، فَأَتَاهُ أَبُو سُفْيَانَ فَقَالَ يَا مُحَمَّدُ إِنَّكَ تَأْمُرُ بِطَاعَةِ اللَّهِ وَبِصِلَةِ الرَّحِمِ وَإِنَّ قَوْمَكَ قَدْ هَلَكُوا، فَادْعُ اللَّهَ لَهُمْ قَالَ اللَّهُ تَعَالَى ‏{‏فَارْتَقِبْ يَوْمَ تَأْتِي السَّمَاءُ بِدُخَانٍ مُبِينٍ‏}‏ إِلَى قَوْلِهِ ‏{‏عَائِدُونَ * يَوْمَ نَبْطِشُ الْبَطْشَةَ الْكُبْرَى‏}‏ فَالْبَطْشَةُ يَوْمَ بَدْرٍ، وَقَدْ مَضَتِ الدُّخَانُ وَالْبَطْشَةُ وَاللِّزَامُ وَآيَةُ الرُّومِ‏.‏